A light year is defined as the distance light travels in one year. One light year is
9.46 × 10^12 kilometers. A galaxy is about 150,000 light years wide. About how
many kilometers wide is the galaxy?
A 1.419 × 10^16
B 1.419 × 10^17
C 1.419 × 10^18
D 1.419 × 10^19

Please give explanation.