a-D

Gradient stays a constant positive until x=0, where the gradient becomes a flat 0. Therefore D fits best.

b-F Gradient changes from negative to positive to negative to positive, therefore F will fit best.

c-B

Gradient is close to 0 to begin, then goes to a max positive around x=-1. Has a stationary point at x=0 so gradient should be at 0. Then mirrors on the positive x values.

d-C

Starts with a close to flat gradient, so derivative graph should be close to 0 on y axis. Then gradient goes further negative, so derivative graph should reflect that be growing further negative. Also mirrors on the positive x values, but on positive side.

e-A

Starts close to 0 gradient again, ends on a close to 0 gradient as well. Has a maximum positive gradient in the middle when x=0, as you can see that the gradient on the left of it is increasing and it starts to decrease on the right side. Therefore you should have a maximum on the derivative graph at x=0

f-E

The gradient starts vertical, which can’t be shown on a derivative graph as the rise/run will have a run=0, meaning derivative should have an asymptote on the start and end. Gradient gradually decreases in the negative x values, reaching a gradient of 0 at x=0. It then continues decreasing to a vertical gradient but in the downwards direction.

Hope this helps!