Complete the following sentence using the correct combination of word…

The correct answer is Option (4) → cleverest / more clever

Degrees of comparison:

• The superlative (the + -est / most) compares one person with all the others in a group: "the cleverest boy in the class".
• When two qualities of the same person are compared, the pattern is more + adjective + than + adjective, never the -er form: "he is more clever than benevolent", not "cleverer than benevolent".
• Complete sentence: Manish is the cleverest boy in the class. However, going by the chatter in the school, he is more clever than benevolent.
  Example: The general was more brave than wise.

Why the Other Options are Incorrect?

Option 1: clever / cleverer — Incorrect.

• "The clever boy in the class" uses the positive degree where a comparison with the whole class needs the superlative.
• "Cleverer than benevolent" uses the -er form to compare two qualities of one person.

Option 2: most clever / clever — Incorrect. "Than" must follow a comparative; "clever than benevolent" is ungrammatical.

Option 3: cleverer / cleverest — Incorrect.

• "The cleverer boy in the class": the comparative is used for two, and a class has many boys.
• "Cleverest than": a superlative is never followed by "than".