(A): The mole fraction of argon in air is 0.95
(R): The volume percentage of all noble gases in air is equal to unity 

Options

A. Both (A) and (R) are true and (R) is the correct explanation of (A)
B. Both (A) and (R) are true and (R) is not the correct explanation of (A)
C. (A) is true but (R) is false
D. Both (A) and (R) are false

Answer

D