It does not make sense with "pathology" in the blanks. One does not "take a pathology".
Student or Learner
So, say I was given the following sentence: The boy took a ______ which tested his blood positive for having cancer.
Or something along those lines. Simple version: The boy took a ___________ which proved he had cancer.
So, apparently, the word in the blank is pathology, or the science of diseases. In my class, we learned it as, the study of diseases.
Does that even make any sense?
The boy took a pathology which proved he had cancer.
The boy took a pathology which tested his blood positive for having cancer.
I honestly don't think it works - even if pathology is taught in the form of, "study of diseases".
I mean, I can understand, "the boy took a study of diseases, which proved he had cancer," but that's not how the word pathology is. It's the actual study, or science of. Not a physical test, or study.
"Blood test" is what makes sense to me.
There is no good reason to begin two sentences with 'So'.