Ubiquitination Exam AAMC Q Spoiler

I am honestly a little confused with this question. Why can't it be C?? In Cell S&F I learned that ubiquitination targets a cell for lysosomal destruction via protease enzymes. I mean I get why A can be correct but why not C?
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Tags: MCAT: Medical College Admissions Test Source Type: forums