Bob does very well on all of his English papers and is praised for his skilled writing. However, when he is around his friends he says things like "ain’t" and "like" often, though his sentences are still grammatical. When writing he is following , while when speaking he is following .

a. prescriptive rules; prohibitive rules
b. syntax; descriptive rules
c. prescriptive rules; descriptive rules
d. prescriptive rules; linguistic universals

C. prescriptive rules; descriptive rules

Explanation: In Grammar, the prescriptive rules could be explained as bindings or rulings on how grammar ought to be or put simply, the ideal way to do speak or write based on standard grammatical rules. The descriptive rules on the other hand describes how a language is spoken with the difference between the two being the strict following of grammatical rules. Descriptive rules is of the notion that variability exist in rules based on usage and differences in the speaker. It isn't rigid on established grammatical rulings.

what is the question you are trying to ask?

it all depends on how long the hours are. i think they wouldn't approve of it. in my opinion.