Read the paragraph. [1] Joe and Mike were curious boys. [2] One day they noticed a large green caterpillar crawling on an apple tree twig. [3] They cut the twig from the tree and put it and the caterpillar in a large glass container. [4] After filling the bottom of the container with leaves from the same tree, they covered the jar with a plastic lid, which had holes in it. [5] For several days they watched as the caterpillar ate fresh leaves and crawled back and forth on the twig. [6] One day they noticed the caterpillar was carefully wrapping itself in a silky cocoon. [7] The boys waited many months for the caterpillar to wake up. [8] Early in June, their wish came true. [9] A big, beautiful, orange and brown moth had dried its wings and laid eggs on the twig. [10] The happy, excited boys had seen the life cycle of a moth.

What is the topic sentence?

3
1
4
10
8
5