Which statement describes a compound machine? a. it has movement in only one direction. b. it can only be acted on by one force. c. it is made up of more than one simple machine. d. it makes work more difficult.

Which of the following can occur to two segments of a population if they are geographically isolated 1.) they can only share some types of genes 2.)both groups most likely become extinct 3.)they find a way to come back together 4.)eventually they become separate species