Pick out the part of the sentence that has an error. A. Manju's fathe…

The correct answer is Option (4) → D only

A. Manju's father — Correct.

• The possessive is right.

B. is the one — Correct.

• "Is" agrees with the singular subject.

C. who is standing — Correct.

• Who is used for a person, and the present continuous suits an action going on now.

D. besides her — Incorrect.

• Beside is a preposition of place meaning next to.
• Besides means in addition to.
• The father is standing next to her, so it should be "beside her".
  Example: Come and sit beside me on the bench.
• Correct form: Manju's father is the one who is standing beside her.

E. no error — Incorrect.

• Part D has an error.

Contrast: "beside" means next to. "Besides" means in addition to.