GMAT Sentence Correction (SC) | Re: Positing an enormous volcanic explosion at the end of the Permian peri

This question tests Parallelism. Parallelism that we need to check may follow either of the 3 below mentionedpatterns-
Pattern 1 - Explain the presence of X, Y, & Z - Correct
Pattern 2 - Explain the presence of X, the presence of Y, & the presence of Z - Correct
Pattern 3 - Explain the presence of X, Explain the presence of Y, & Explain the presence of Z - Correct

A) Follows Pattern 2, But use of ACCOUNT FOR is unjustified. Hence Incorrect
B) Follows Pattern 1. Hence