The following is/are not a unit of time:

(a) second
(b) parsec
(c) year
(d) light year


Choose the correct option:

1. (a, c, d)
2. (a, c)
3. (b, d)
4. (b, c)

(3) 

Hint: Light year and parsec are the units of length.

Step 1: Differentiate the unit of length and time.

We know that 1 light year = 9.46 x 1011 m
              = distance that light travels in 1 year with speed 3x 10 m/s.
 1 parsec = 3.08 x 1016 m
              = Distance at which average radius of
                 earth's orbit subtends an angle of 1 per second
Here, the second and year represent time.