Please help me I am struggling :((

How do you do this geometry problem

Given this information, which expression must represent the value of b?

What is true about the dilation? it is a reduction with a scale factor between 0 and 1. it is a reduction with a scale factor greater than 1. it is an enlargement with a scale factor between 0 and 1. it is an enlargement with a scale factor greater than 1.