Which index should Jan use as a benchmark when evaluating the performance of her XYZ mutual fund?

Index 1 Index 2 Index 3 Index 4

Beta 0.75 1.1 1.25 1.5

r-squard 0.80 0.90 0.95 0.50

a.) Index 1

b.) Index 2

c.) Index 3

d.) Index 4

Please explain.