Fill in the blank with a suitable a Preposition. I saw the teacher __…

The correct answer is Option (2) → C only

Prepositions of place and movement:

• In shows position inside a place or building.
• Into and onto show movement towards the inside or the surface of something.
• This sentence: "saw" tells where the teacher was, not where he moved, so the preposition of position "in" fits.

Complete sentence: I saw the teacher in the school.

A. on — Incorrect.

• "On" shows position on a surface ("on the table").
• A person is in a school, not on it.
  Example: The keys are on the table.

B. onto — Incorrect.

• "Onto" shows movement to a surface.
• There is no movement in the sentence.
  Example: The cat jumped onto the wall.

C. in — Correct.

• It shows the teacher's position inside the school.

D. into — Incorrect.

• "Into" shows movement to the inside of something and goes with verbs of motion.
  Example: She walked into the room.

Contrast: in tells where someone is (I saw the teacher in the school). Into tells where someone moves (She walked into the room).

Tip: In this question the options do not follow the order of the statements (Option 1 = A only, Option 2 = C only, Option 3 = B only, Option 4 = D only). NTA often jumbles the options in this way, so after finding the correct statement, read the options carefully and mark the one with the right letter.