Is the main idea of the following paragraph stated or implied?

Gum chewing has been occurring in classrooms for decades. Many teachers are distracted by the constant sound of gum chewing while they teach class. Teachers often have to remove gum from the backs of desks or from classroom floors. The gum is unsanitary and unsightly.

A.
stated

B.
implied

B. implied

The main idea of the paragraph is implied.