How many factors should a well designed experiment test at one time

Sarah and john are having a discussion on genetic diversity. sarah believes that it happen over a long period of time. john it happens immediately. who is correct? a. sarah is correct because genetic diversity occurs over a long period of time. b. john is correct because genetic diversity occurs immediately. c. both are correct because genetic variation can occur or long period of time. d. neither are correct because genetic diversity occurs over any period of time

9. what area of study applies scientific findings to create ways for solving problems or improving life? a biogeology b mathematics c manufacturing d engineering

Does all the energy stored by the phytoplankton reach the top level of the pyramid