Angry Birds has become a worldwide gaming mega hit but how did this game come into existence? Rovio is the name of the company that created angry birds, however, it's not the first game they developed. Surprisingly they have been creating games for several years but had just never broken through into the mainstream the way they did with angry birds. The idea for the game came about in 2009 when the company was looking at different ideas for games which they thought could become popular. It was a simple idea _ from some sketches  of wingless and legless birds which were angry. The sketches caught on among the staff who in turn created a unique design which became angry birds. The pigs were added into the game later in the development as an enemy. During this period of development, pig flu was being heavily reported in the news which is where the idea for the pigs appeared. The basis of the game is very simple and is not unique to angry birds but has been seen in many other games previously. It's a simple physics/puzzle game. The player is given a slingshot and a limited supply of angry birds with different characteristics. Some birds are faster than others while others can be split into multiple birds. You control the trajectory  of the birds with the slingshot which launches them towards rickety structures containing your main enemy, the pigs. In order to advance to the next level you must eliminate  all of the pigs before your birds run out. Rovio has released several different versions of the game at this point. The original, Seasons, and Rio. Seasons is a collection of holiday themed versions of the game while Rio was a movie tie in for the movie Rio. All versions continue to be updated with new levels which are free to those who have previously purchased the game. According to the text, the game players   _  .
must pay for this game--angry birds one level by one level only pay for once and then it will be updated freely should control angry birds to kill all the animals with pig flu will become angry easily for playing the game too much
Question: Angry Birds has become a worldwide gaming mega hit but how did this game come into existence? Rovio is the name of the company that created angry birds, however, it's not the first game they developed. Surprisingly they have been creating games for several years but had just never broken through into the mainstream the way they did with angry birds. The idea for the game came about in 2009 when the company was looking at different ideas for games which they thought could become popular. It was a simple idea _ from some sketches  of wingless and legless birds which were angry. The sketches caught on among the staff who in turn created a unique design which became angry birds. The pigs were added into the game later in the development as an enemy. During this period of development, pig flu was being heavily reported in the news which is where the idea for the pigs appeared. The basis of the game is very simple and is not unique to angry birds but has been seen in many other games previously. It's a simple physics/puzzle game. The player is given a slingshot and a limited supply of angry birds with different characteristics. Some birds are faster than others while others can be split into multiple birds. You control the trajectory  of the birds with the slingshot which launches them towards rickety structures containing your main enemy, the pigs. In order to advance to the next level you must eliminate  all of the pigs before your birds run out. Rovio has released several different versions of the game at this point. The original, Seasons, and Rio. Seasons is a collection of holiday themed versions of the game while Rio was a movie tie in for the movie Rio. All versions continue to be updated with new levels which are free to those who have previously purchased the game. According to the text, the game players   _  .
A. must pay for this game--angry birds one level by one level
B. only pay for once and then it will be updated freely
C. should control angry birds to kill all the animals with pig flu
D. will become angry easily for playing the game too much
Answer: