Assertion (A): The system x − y = 3 and x − y = k has unique solutions for every real value of k.
Reason (R): Two lines in a plane can never intersect.

a. Both A and R are true, and R is the correct explanation of A.
b. Both A and R are true, but R is not the correct explanation of A.
c. A is true, but R is false.
d. A is false, but R is true.