Which question would be asked in a dichotomous key?

How long are the insect's antennae?

Are the insect's antennae longer than its head?

Are the insect's antennae long or short?

How does the insect use its antennae?

Are the insect's antennae longer than its head?

Explanation:

This character is easily measurable and allows insects to be grouped into two groups, those that have the antennae longer than their head and another group of those that have the antennae shorter than their head. A dichotomous key is based on the fact that two possible solutions start from it, depending on whether or not they have a certain character, and it needs to be constructed by pairs of opposing statements like in this case antennae longer than its head and shorter are opposite

Are the insects antennae longer than its head.