Before reading a text it is to have about the subject. a. prior knowledge c. an opinion b. sensory details d. all the facts

Before reading a text it is helpful to have (A.) prior knowledge about the subject.

Explanation: Prior knowledge can be understood as the knowledge that a person has already acquired and developed before dealing with a new text. Having prior knowledge about the subject of a text makes the reading much more easier, especially in those cases in which specific terminology is used.  In other words, prior knowledge contributes to facilitate the comprehension of a new text. Moreover, it also allows the readers to incorporate a larger amount of new information into their minds.  

where exactly is the sentence

the conclusion would be the most affected category scoring