Question

what is an intermediate step in the evolution of light bulbs, between incandescent bulbs and led bulbs? fluorescent lights led lights incandescent lights

Explanation:

Incandescent bulbs were the earliest common lighting technology, followed by fluorescent lights which are more efficient than incandescents, and then LED bulbs which are the most modern and efficient option among the choices. LED and incandescent bulbs are the endpoints of the stated evolution, so they cannot be the intermediate step.

Answer:

fluorescent lights