Excused from recycling  because you live in a high rise with a rubbish chute  ? You won't be for long. Miami's Mark Shantzis has made it simple for those living in tall buildings to use the chute and recycle too . In Shantzis' Hi-Rise Recycling System, a chute leads to a pie-shaped container with six boxes that can turn around when operated. The system , which fits in the same space as the chute and container now in use, enables glass , plastic , paper , metal , and other rubbish to go into separate boxes . The system is controlled from a board next to the chute door. The board has a button for each class of recycling materials (as well as for unrecyclables). At the press of a button, a microcomputer locks all other floors' chute door and sets the recycling container turning until the right box comes under the chute. The computer also counts the loads and gives a signal by phone when the box is full. And a particular piece of equipment breaks up the nonrecyclables Sorting  recyclables before they are collected saves the use of expensive materials recovery equipment which otherwise has to do the sorting . Such equipment often makes recycled materials very expensive, so expensive that tons of recyclables remain wasted . Shantzis believes his system could help recycled materials become more cost-effective. Before dropping rubbish into the chute you have to   _
lock the other floors' chute doors check if the container is full press the correct button break up the rubbish
Question: Excused from recycling  because you live in a high rise with a rubbish chute  ? You won't be for long. Miami's Mark Shantzis has made it simple for those living in tall buildings to use the chute and recycle too . In Shantzis' Hi-Rise Recycling System, a chute leads to a pie-shaped container with six boxes that can turn around when operated. The system , which fits in the same space as the chute and container now in use, enables glass , plastic , paper , metal , and other rubbish to go into separate boxes . The system is controlled from a board next to the chute door. The board has a button for each class of recycling materials (as well as for unrecyclables). At the press of a button, a microcomputer locks all other floors' chute door and sets the recycling container turning until the right box comes under the chute. The computer also counts the loads and gives a signal by phone when the box is full. And a particular piece of equipment breaks up the nonrecyclables Sorting  recyclables before they are collected saves the use of expensive materials recovery equipment which otherwise has to do the sorting . Such equipment often makes recycled materials very expensive, so expensive that tons of recyclables remain wasted . Shantzis believes his system could help recycled materials become more cost-effective. Before dropping rubbish into the chute you have to   _
A. lock the other floors' chute doors
B. check if the container is full
C. press the correct button
D. break up the rubbish
Answer: