When purchases of tennis socks decline following an increase in the price of tennis sneakers (other things remaining equal), the relationship between these two items can be described as

A) substitutable.

B) complementary.

C) unique.

D) ordinary.

Option B Complementary

Explanation:

The reason is that increase in one product (Sneakers) purchases increases the purchases of other product (socks) which is compulsory. In this case we see that the sneakers prices have increased which led to decrease in sales of sneakers and also a decrease in the socks sales is witnessed. This is beacause the sale of one product is directly proportional to other and this relation is also known as complementary relation among products.