Fill in the blanks with the most appropriate option:-

It’s 7:30 PM …….. my watch.

by

The correct option to fill in the blanks is by.

The sentence is about the time according to the speaker's watch. The preposition "by" is used to indicate the means by which something is done. It is the most appropriate preposition to use in this context, as it describes the means by which the speaker knows the time.

The other options are not as appropriate:

• In can be used to indicate the location of something. It is not accurate to use "in" in this context, as the time is not located on the speaker's watch.
• On can be used to indicate the date or time of something. It is not accurate to use "on" in this context, as the time is not the date or time of the speaker's watch.
• From can be used to indicate the source of something. It is not as appropriate as "by", as it does not convey the same sense of means or agency.
• To can be used to indicate the destination of something. It is not as appropriate as "by", as it does not convey the same sense of means or agency.