This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to catch a firefly
Search in the right places for fireflies.
Fireflies live in various habitats, including forests and rivers. They tend to be drawn to high grass and humid, damp areas.

Possible answers: (I) Rivers are notorious for sucking-flies into bubbleheads, dry land, and shady areas, where the area is prone to people or wildlife. Insect habitats are also a better bet for keeping pickled or sick fireflies, as they form colonies near entryways where they feed on nectar and chemicals. (II) If you encounter them, try to look in them while you walk through them or wait to see where they live. Fireflies are easiest to catch, however, and you should be able to find them in places like rocky or thoroughly drained areas. (III) If you're trying to catch a firefly, pay attention to bright, visible fireflies. Sometimes fireflies will appear in grassy areas of the himalayan area. (IV) They are found all over the world, from the americas to europe and asia. In the united states, fireflies are rarely found west of the rocky mountains.
The answer is:
(IV)