Economic Theory Provides a Basis for Which Variables Are Relevant

Economic theory provides a basis for which variables are relevant and should be included in an econometric model.But econometrics provides tools to estimate ____________________ which tells us ________________________________.

A) a model,the functional form that should be used.
B) causality,why it happens that way
C) a parameter,how much or to what degree things change.
D) variables,the probability of a specific outcome.