Directions: In this question, a sentence is given with a blank to be filled in with an appropriate word. Choose the correct alternative out of the four given alternatives.

Students had to face _______ challenges.

Explanation for option 1: “Lots” should be followed by “of”. So, it is incorrect. Explanation for option 2: This does not make a meaningful sentence. Explanation for option 3: “Sum “means “total” and this does not fit in the given context. Explanation for option 4: This is a valid option as it clearly conveys that students had to face numerous (many) challenges.