Lets Think.
If frog population declines all of a sudden `:`
Number of which consumers will decline and which will increase ?

Explanation

If the populaion of frog declines, then the number of primary consumers, like grasshoppers will increase as the frog that feed upon grasshoppers have reduced in number, whereas the number of tertiary consumers like snakes will decrease as the frogs on which they feed have decreased in number.