Saad often ____ late at night.

The correct answer is Works because the adverb 'often' signifies a habitual, repeating action, requiring the simple present tense with proper subject-verb agreement.

• Works: This is the correct choice. The sentence describes a regular habit or routine. In English grammar, habitual actions are expressed using the simple present tense. Since the subject 'Saad' is singular (third-person singular), the verb must take an '-s' ending ('works').
• Incorrect Options:
  • Work: This is incorrect because it is a plural base verb, which violates subject-verb agreement when paired with a singular third-person subject like Saad.
  • Worked: This is incorrect because 'often' typically sets up a prevailing routine in the present tense unless a explicit past time marker (like 'last year') is provided.