Fill in the blanks with the most appropriate option:-

It is half past six .......my watch.

by

The correct option to fill in the blanks is by.

The phrase "by my watch" is an idiom that means "according to my watch". It is used to indicate that the time is being given according to the speaker's watch. The preposition "by" is used to indicate means or method. It is the most appropriate preposition to use in this context, as it describes the way in which the time is being determined.

The other options are not as appropriate:

• In can be used to indicate location, but it is not as appropriate as "by", as it does not convey the same sense of means or method.
• With can be used to indicate association or possession, but it is not as appropriate as "by", as it does not convey the same sense of means or method.
• About can be used to indicate a rough estimate, but it is not as appropriate as "by", as it does not convey the same sense of accuracy or precision.