What does Light year Measured?

Option C

A light-year is how astronomers measure distance in space. 

The light-year is a unit of length used to express astronomical distances and measures about 9.46 trillion kilometres (9.46 x 10¹² km) or 5.88 trillion miles (5.88 x 10¹² mi).As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in vacuum in one Julian year (365.25 days). Because it includes the word "year", the term light-year may be misinterpreted as a unit of time.