Adam is writing a research paper about recycling, and he has several potential research questions. Which is his best option?
AHow many US cities have recycling programs?
BWhy didn’t people start recycling earlier in history?
CWhat are the effects of recycling on the environment?
DWhich materials are recyclable?
AHow many US cities have recycling programs?
BWhy didn’t people start recycling earlier in history?
CWhat are the effects of recycling on the environment?
DWhich materials are recyclable?