hmmm ... interesting ...
The mouth, in many psychiatric texts, is viewed as a portal of entry as well as an expression of the soul. The immediate gratification of "taste" is also extremely powerful, with seminal and vaginal fluid rich in pheromones, it stimulates neural transmissions that triggers hormonal, emotional, thus physical changes that can overwhelm the other senses, or even logic, leading to heightened states of arousal ...
I just made that up
Please disregard!
I don't know, I am not a psychiatrist! But as Dr. Hellminth on TV, I would say c) - coz I am into orals and can't see any reason why it should be discouraged unless you see a rash, blisters or something moving among the bushes.