The correct answer is B. Marking up the text during reading is necessary for critical thought and helps readers make connections to what they read.
Explanation:
One basic grammar rule is that the subject and verb should be consistent in terms of number (plural vs singular). This means in a sentence with a singular subject the verb should be singular, and adding a plural verb would be incorrect.
In the case of the sentence presented, the subject is " Marking up the text" and this is a singular subject because it refers to one specific purpose. In this context, the verbs "be" and "help" need to be in the singular form, which is "is" and "helps". This only occurs in the second sentence or option.
