Question

One astronomical unit is a distance equal to
1. 9.46*1015
2. 1.496*1011
3. 3*108
4. 3.08*1016

Answer 1

AU : One Astronomical Unit (AU) is the average distance between the Sun and the Earth.

From that, your answer is option 2.

That is, 1 AU = 1.496 × 10^11 m

Just for info:
Option 1 is the distance of light year (ly) . One light year is the distance light travels in one year in vacuum.

Option 4 is the distance of 1 parsec (pc).

One Parsec is the distance at which 1 AU subtends an angle of exactly 1 second of an arc.