Which method of birth control prevents the implantation of the fertilised egg?

Question

1. coil (mechanical)
2. condom (mechanical)
3. spermicide (chemical)
4. vasectomy (surgical)

I don't get the question. The correct answer was number 1, but shouldn't all the options be correct?? I wrote 4 by the way.

Answer 1

With condoms, spermicides, and a vasectomy, the eggs are not fertilized.

Note the origin of the word "spermicide" -- it's a killer of sperm.