Use the Following to Answer Questions

Multiple Choice

Use the following to answer questions:
Refer to the graph below.

-Which factor best explains why environment might be a confounding variable in comparisons across groups in the graph?

A) Some pairs of relatives share more genes than other pairs of relatives.
B) Close relatives tend to be raised in similar surroundings.
C) Compared with close relatives, distant relatives have fewer close relatives in common.
D) Many external sources of stress are unaccounted for in research.