The option in which the relative pronoun can be omitted ...

A “… they begin to learn to analyze literature and participate in an educational process that they will find more interesting than a general lecture on a chapter in a book” (lines 41-45). B “… or use interactive vocabulary-building exercises which relate to the class’s reading material” (lines 14-16). C “This learning strategy is useful for English teachers who incorporate literature into their classroom” (lines 35-37). D “…teachers must employ effective strategies that allow each student to learn the material” (lines 3-5).