Fill in the gaps with appropriate preposition: Nazia was born _____ 2008, ______ 12 June, _________ 7 o'clock.

Prepositions of time
We can use prepositions of time to say when things happen.

- Use in months and years, on before days and dates, and at before times.

Examples: 

I was born in April.
He goes to the park on Saturdays.
She wakes up at 07.00.
How to use them

সুতরাং, সঠিক উতরটি হবে, in, on, at 

More examples: 

in January / July / 2014
on Monday / Friday / 1 May
at 11.30 / 4 o'clock / half past two
She was born in 2008, on 12 June, at 7 o'clock.
We use on with special days and at with special times too.

on my birthday / New Year's Day / the last day of school
at midnight / bedtime / dinner time
At bedtime on Halloween we usually read a scary story!
We use in with parts of the day and at with night.

in the morning / afternoon / evening
at night
I don't like going to bed at night but I like getting up in the morning.

Source: Essential Grammar in Use by Raymond Murphy & Cliffs TOEFL