An advantage of matching a variable across treatments rather than using random assignment to form your groups is that a. matching reduces error due to participant differences.  b. matching is easier...

An advantage of matching a variable across treatments rather than using random assignment to form your groups is that

a. matching reduces error due to participant differences.

 b. matching is easier than randomization.

 c. matching guarantees that there is no systematic relationship between participant characteristics and the treatment conditions.

 d. matching ensures a nonbiased sample.