Which one of the following longitudes is the standard meridian of Indi

Which one of the following longitudes is the standard meridian of India ?

83°30' E
82°30' E
82°30' W
83°30' W
This question was previously asked in
UPSC CDS-1 – 2021
The standard meridian of India is 82°30′ E longitude. This longitude passes through Mirzapur in Uttar Pradesh and is used as the reference for Indian Standard Time (IST).
The standard meridian is chosen to be roughly in the middle of the country’s longitudinal extent to minimize the time difference between the eastern and western parts of the country.
IST is 5 hours and 30 minutes ahead of Coordinated Universal Time (UTC) or Greenwich Mean Time (GMT). The longitudinal extent of India is roughly from 68°7′ E to 97°25′ E.