Arrange the following in order of decreasing extension.

The order of decreasing extension runs Food products, Dairy products, Cheese, Cottage cheese.

Extension is the range of things a term covers, so the arrangement moves from widest to narrowest.

Food products is the broadest class, so it comes first.

Dairy products is a narrower class inside food products, and cheese is a narrower kind of dairy product.

Cottage cheese is one specific cheese, the narrowest, so it comes last.

So the decreasing sequence is 2, 3, 1, 4.