Answer: The right answer is indeed "compeling," which should be spelled "compelling."
Step-by-step explanation: Just to elaborate a little on the answer, it can be added that one of the rules of the English language states that the words that end with a consonant-vowel-consonant pattern, like compel, get a double consonant when they are followed by ED or ING, as in compelling. In addition, in two-syllable words, like compel, if the stress is on the second syllable, as in compel, the word gets a double consonant when it is followed by ED or ING, hence the reason to write compelling with a double l.