Correct Answer - Option 2 : distance
Explanation:
Parsec (parallactic second):
- It is the largest practical unit of distance used in astronomy.
- It is defined as the distance at which an arc of the length of 1 astronomical unit subtends an angle of 1 second of arc.
1 parsec = 3.08 × 1016 m
So clearly, it is the unit of distance.
- Another unit of distances are light year, Angstrom.
- SI unit of distance or lengrh is meter.
- SI unit of time is second.
- SI unit of frequency is hertz.
- SI unit of angular acceleration is sec - 2.