Choose the suitable Preposition to fill in the blank in the given sentence:

It is ten o'clock _____ my watch.

by

The correct answer is Option (1) → by

• The correct phrase is "by my watch", which means according to the time shown on my watch.
• Example: It is ten o'clock by my watch.

OTHER OPTIONS

 "In my watch" – Incorrect, as we do not use "in" when referring to time shown on a watch.
  "On my watch" – Incorrect, as "on" is used for surfaces, not for referring to time.
  "For my watch" – Incorrect, as it does not make sense in this context.