Answer:
Letter K.
Step-by-step explanation:
The letter c with vowels a, or i, or o, or vowel u produces the letter k's sound. Also, the q followed by ui, or ue makes the letter k's sound.
It is crucial to notice that the c followed by vowel e does not produce the letter k's sound. Besides, QU can only be preceded by the i and e, and it will sound like a k.