A light - year is a unit of _________ .

Correct option is B

The correct answer is (b) Distance 

Explanation: A light - year is a unit of Distance 

Information Booster: A light-year is a unit of distance that measures how far light travels in one year:

• Definition- A light-year is the distance light travels in a vacuum in one Julian year, which is 365.25 days.
• Value- One light-year is equal to 9,500,000,000,000 kilometers, or about 5.88 trillion miles.
• Use Light-years are often used in astrophysics to measure the distance between astronomical objects.
• Symbol- The symbol for a light-year is "ly" or "lyr".
• Not a unit of time- Although the term includes the word "year", a light-year is not a unit of time.