I'm pretty sure the answer's a bit obvious.
A condom helps prevent the spread of sexually transmitted diseases.
So A.
"A"
The answer option "A" is the only legitimate answer backed by solid proof. it does not make ridiculous statements or proves a ridiculous point like the others. There is no way the other answer options have such causes and effects, and are highly contraindication, and i would always highly recommend getting knowing your family history as genes play a lot in healthcare.
Applying soap to one's hands be made after wetting with clean (warm or cold) water then turning off the tap.