Answer:
CNTNAP2.
Explanation:
Contactin-associated protein-like 2 (CNTNAP-2) is a protein coded by its respective gene CNTNAP2 gene. This is one if the longest gene present in the human genome.
This gene plays an important role in the speech and ability of an individual. The mutation in the CNTNAP2 gene can cause different diseases like schizophrenia, autism and also associated with the Tourette syndrome in which the speech ability of individual get disrupted.
Thus, the correct answer is option (b).