If it is possible to make a meaningful word with the fourth, the eighth and the tenth letters of the word 'COUNTERACT', which of the following will be the last letter of that word ? If no such word can be made, give X as the answer. If more than one such word can be made, give M as the answer.
The fourth, eighth and tenth letters of the word COUNTERACT are N, A and T respectively. The words formed are ANT and TAN.