Pelvic inflammatory Disease - Infertility

I am stuck on this homework question, I'm not sure if I am stuck on the wording but I am thinking between C and D. My studies have shown that both the egg and the sperm enter the fallopian tube that has been blocked by damage so I am totally confused. Any explanation is greatly appreciated.


Untreated chlamydia and gonorrhea can lead to pelvic inflammatory disease in women. Pelvic inflammatory disease (PID) can cause a buildup of scar tissue on the Fallopian tubes.

Women affected with PID can become infertile because
Select one:
a. the fertilized egg cannot implant on the endometrium
b. the ovaries cannot secrete the necessary hormones to support an embryo
c. the ovum cannot be swept into the Fallopian tube
d. sperm is blocked from entering the Fallopian tubes to fertilize the egg