Regarding causes of infertility, it is the case that

A irregular or failed ovulation is the most common cause of female infertility
B infertility lies in fertility problems of the male partner in about 12% of cases.
C endometriosis result from repeated failure to ovulate
D sperm motility is directly correlated to sperm count

I belive the correct answer is A

I believe you're right.

Blocked fallopian tubes — generally resulting from PID (Pelvic Inflammatory Disease) — is the leading cause of female infertility. This is a problem with fallopian tubes rather than ovulation.

Although they may have changed, my statistics for male infertility problems is 18% rather than 12%.

Frankly, I can't see a correct answer for this question as you have stated it.

Sorry that I can't be more helpful. Thanks for asking.

To determine the correct answer, let's go through each option:

A) Irregular or failed ovulation is indeed the most common cause of female infertility. Ovulation is the release of an egg from the ovary, and when it doesn't happen regularly or doesn't happen at all, it can make it difficult for a woman to conceive.

B) Infertility due to fertility problems in the male partner is a possibility, but the statement says it occurs in about 12% of cases. It implies that it is not the most common cause.

C) Endometriosis is a condition in which the tissue that usually lines the inside of the uterus grows outside the uterus. It is not directly caused by repeated failure to ovulate, so this option is not correct.

D) Sperm motility refers to the ability of sperm to move properly. While sperm count is the number of sperm present, it is not directly correlated to sperm motility. This option is incorrect.

Therefore, the correct answer is A) Irregular or failed ovulation is the most common cause of female infertility.