Math prob transformation of graph

Can anyone help me with this..

How would I got abouts finding the answer to this question. Thanks for any help!

1. The graph of -

3f(x) can be obtained by (a) stretching the graph of f(x) vertically by a factor of 3.

(b) stretching the graph of f(x) vertically by a factor of 3, and also reflecting the graph vertically.

(c) stretching the graph of f(x) horizontally by a factor of 3.

(d) stretching the graph of f(x) horizontally by a factor of 3, and also reflecting the graph hori-

zontally.