More than 15 million Britons, many of them women, will holiday unaccompanied this year. And they will no longer be treated as second-class citizens. After 50 years of being slighted, ripped off, herded together and allocated the worst rooms in the hotel, the single traveller's time has finally come. Rather than being viewed as an awkward peculiarity in the standard couples-and-families "system", single travelers have become travel's fastest growing sector and a phenomenon that tour operators are falling over themselves to catch up with. In one sense, the boom is the result of people postponing marriage and children. Approximately 39% of the adult British population--19 million people--is now single and the proportion of one-person households has increased from 18% in 1971 to 29% last year. The most significant growth of singles over the next few years is expected to be within the well-off, travel-hungry 25-34 age group.  The expansion in single travel is being increased by women. Women are just as happy as men to leave partner at home and head off on holiday. On adventure group trips single women constitute more than half of all travelers, and Internet agents report that 70% of their single clients are women.     Women today see being single as an opportunity to travel, rather than as an obstacle. The result is that travel companies are now attempting to work out new ways of attracting singles----a market worth PS10.4 billion. The number of specialist singles tour operators has risen from a couple to at least 10, but they face a growing challenge from mainstream operators, who now propose to target solo travelers with moves like abolishing single room supplements. At the moment, single travelers usually have to join a group, or pay more. As soon as we get beyond that, the singles market is going to take off to a completely new level. The number of solo travelers is increasing due to   _  .
an increased divorce rate delaying of marriage people changing careers couples not having children
Question: More than 15 million Britons, many of them women, will holiday unaccompanied this year. And they will no longer be treated as second-class citizens. After 50 years of being slighted, ripped off, herded together and allocated the worst rooms in the hotel, the single traveller's time has finally come. Rather than being viewed as an awkward peculiarity in the standard couples-and-families "system", single travelers have become travel's fastest growing sector and a phenomenon that tour operators are falling over themselves to catch up with. In one sense, the boom is the result of people postponing marriage and children. Approximately 39% of the adult British population--19 million people--is now single and the proportion of one-person households has increased from 18% in 1971 to 29% last year. The most significant growth of singles over the next few years is expected to be within the well-off, travel-hungry 25-34 age group.  The expansion in single travel is being increased by women. Women are just as happy as men to leave partner at home and head off on holiday. On adventure group trips single women constitute more than half of all travelers, and Internet agents report that 70% of their single clients are women.     Women today see being single as an opportunity to travel, rather than as an obstacle. The result is that travel companies are now attempting to work out new ways of attracting singles----a market worth PS10.4 billion. The number of specialist singles tour operators has risen from a couple to at least 10, but they face a growing challenge from mainstream operators, who now propose to target solo travelers with moves like abolishing single room supplements. At the moment, single travelers usually have to join a group, or pay more. As soon as we get beyond that, the singles market is going to take off to a completely new level. The number of solo travelers is increasing due to   _  .
A. an increased divorce rate
B. delaying of marriage
C. people changing careers
D. couples not having children
Answer: