Linear Regression: Introduction

Question

Which one of the following best represents the goal(s) of linear regression?
-Given data points {(Xi, Yi)} , try to explain why Y is changing depending on X.

-Given data points {(Xi, Yi)} , fit a model and try to predict Y given a value for X .

-Given data points {(Xi, Yi)}, prove that the relationship between Y and X is linear.

-Given data points {(Xi, Yi)}, obtain the functional relationship between Y and X.