What is a well-known issue with cross-sectional methodology?

This methodology enables to measure simultaneously both the result and exposure in the group under study

Explanation:

A cross-sectional method is a type of scientific design based on observational data. The cross-sectional studies involve the use of diverse groups that differ in the variable investigated but share other features (for example, individuals with the same educational background, ethnicity, economic status, etc). This class of studies is generally used in developmental psychology.

i think that the best answer would be c.

tell me if im wrong : )

if you listed your answers right then i believe your answer is b.