_________ is a process in which the intermediate value of some ...

[joblessjake]

_________ is a process in which the intermediate value of some characteristic is more adaptive than is the value at either end of the distribution.
 
  a. Adaptive selection
  b. Allele selection
  c. Directional selection
  d. Stabilizing selection

Question 2

The use of random assignment is based on a specific assumption. Identify/explain that assumption.
 
  What will be an ideal response?

[sierrahalpin]

Answer to Question 1

D

Answer to Question 2

If you study enough people, any important differences between them (and from other sources) will balance out between groups. Each group will, therefore, be likely to have as many depressed people, confident people, or people with any other trait that might be important.