There are a few big problems with (B).
First, "which enables" is a noun modifier, so it needs to modify the preceding noun. However, we want to modify AART, so this doesn't work. Even if we wanted to modify "carbon nanotubes," we would then need to say "enable" rather than "enables."
An even quicker way to spot this modifier problem is to notice that the word "which" is preceded by a semicolon. This means that the two parts of the sentence should be independent clauses that can work as sentences on their own. Let's look at them:
AART, a procedure that replicates heart arteries using carbon nanotubeswhich enables people with a weak heart to participate in sports to lead a healthy life like a normal person.Notice that neither of these is a complete sentence. The first one has a subject (AART) with no verb, while the second one is a modifier ("which . . . ") with nothing to modify. This makes the use of a semicolon here incorrect.
In fact, even if we put these two pieces together with a comma, we still wouldn't have a sentence! I see "AART . . . a procedure . . . which . . .," but we still have no verb for AART. This is a big problem. This "sentence" is all subject and modifiers, with no action! (Yes, there are verbs in the sentence, but they are all in the modifiers.)
One last problem is in the modifier itself:
which enables people with a weak heart
to participate in sports to leadWe're missing the word "and"! I can't say "this program allows me to teach to learn." We need something to link those items.
Other than that, I love (B).
I hope this helps.