Sharing a dinner utensil
STIs stands for Sexually Transmitted Infections, which are infections due to bacteria, viruses or parasites transmitted while intercourse or contact with that zone genital to genital.
Among the options, sharing a dinner utensil doesn't represents a risk of getting an STIs, because genitals are not involved basically.
Therefore, the right answer is C.
The answer is c. not b.
The correct answer is option C, sharing a dinner utensil
a. through pregnancy