Talon cusp can be seen in:: (A) Mohr syndrome, (B) Rubinstein Taybi syndrome, (C) Sturge - Weber syndrome, (D) All of the above
Answer is D. Talon cusp is an additional cusp that is usually located on the lingual surface of anterior teeth. It extends atleast half the distance from the cemento-enamel junction to the incisal edge. It is composed of normal enamel and dentin and contains a horn of pulp tissue.
It is seen in: 

Mohr syndrome
Rubinstein Taybi syndrome
Sturge-Weber syndrome