A Researcher Has Observed That Children Who Eat More Sugar

Multiple Choice

A researcher has observed that children who eat more sugar tend to show a higher level of activity than children who eat less sugar.However,the researcher suspects that the apparent relationship may be explained by the fact that some children have a higher rate of metabolism,which causes them to eat more and to be more active compared to children with a lower rate of metabolism who eat less and are less active.This is an example of the ____.

A) ​directionality problem
B) ​third-variable problem
C) extraneous variable problem
D) ​manipulation check problem