The correct answer is C. Coman
Grammatical concordance is an idiomatic resource that allows sentences to be coherent, that is, everything is in the same verb tense and the same number. In the case of the sentence of the question, it can be affirmed that the number is plural because it refers to "los niños" (a word in spanish that refers to the word children), so the verb must be in the plural number, and whoever enunciates the sentence refers to the third person, so the proper verb would be "coman" (a word in Spanish that refers to the activity of eating conjugated in a present tense and in plural number, corresponding to the third person). On the other hand, it is necessary to refer to the fact that in most cases the plural verbs in Spanish end with the letter "N". So, the correct answer is C.