Why does rgfp bind to the ni +2 agarose column

Question

Problem:

Question 1: Why does rGFP bind to the Ni +2 agarose column?

Question 2: What fraction should have the most rGFP activity: W1 ,W2, E1, E2

Question 3: What fraction should have the most total protein: W1, W2, E1, E2

Please read all the questions carefully and answer them.