Question

incessantly has the same or almost the same meaning as:
necessarily
certainly
endlessly
indefinitely

Explanation:

The word "incessantly" means without stopping or continuously. "Endlessly" also implies without end or continuously, having a similar meaning. "Necessarily" refers to something being required or inevitable, "certainly" means without a doubt, and "indefinitely" means for an unlimited time or without a fixed end - but not the same as continuous action like "incessantly".

Answer:

C. endlessly