Which punctuation mark belongs at the end of the sentence?

close the refrigerator door

a.
?

b.
.

c.
!

Type the correct answer in the box. spell all words correctly. certain species of insects introduced accidentally in a forest are destroying all the douglas fir trees in that forest. the wood of these trees is extensively used for construction. in order to control the damage caused by these insects, the forestry department decided to introduce the moth caterpillar in the forest. these caterpillars are natural predators of the insects. which method did the forestry department implement to control the invasive species? the forestry department implemented a(n) control method.