IVF works by using a combination of medicines and surgical procedures to help sperm fertilize an egg, and help the fertilized egg implant in your uterus. ... Then they put 1 or more fertilized eggs (embryos) directly into your uterus. Pregnancy happens if any of the embryos implant in the lining of your uterus.
A logical fallacy is a common error in reasoning.
You need a slight stop there to collect your thoughts, especially when the next word is achromatopsia. That makes D wrong.
If you use B, " A medical condition that limits her vision" is not a sentence. So B shouldn't be the answer. Fragments are used by very good writers usually in fiction, and this statement is not part of something that is fictional.
A semicolon separates two equal clauses. You can think of it as meaning "and" or even "but" sometimes. You have the same problem with C as you do with B. So C is not correct.
That leaves us with A. That should be your answer.You need a pause of some kind and that pause is proved by the comma. The sentence is not a run on sentence just one in need of a pause in the middle.
