@Brian_BH 400731’s rationale is great! Could you provide the rationales for QIDs 403409 & 402052?
Got you: 
403409: Question requires multiple approaches, but inherent in the question is the necessity of knowing the single-letter code for glutamate, so as to identify it which is a prerequisite for then applying its pka to determine relative protonation. Being able to identify that it is, indeed, glutamate is necessary to select the correct answer from other single-letter amino acid codes present.
402052: Question requires familiarity with glutamate in order to predict the change in net charge of a polypeptide; requires knowledge of the structure, polarity, and relative acidity of glutamate specifically relative to other amino acid discriminators that would not have the suggested effect on polypeptide pH. Explicit knowledge of the three-letter code, and polarity of the amino acid is necessary to successfully answer the question.