JEE Main 2021 Mathematics question

Consider the system of linear equations –x + y + 2z = 0, 3x – ay + 5z =1, 2x – 2y – az = 7. Let be the set of all a for which the system is inconsistent and be the set of all a for which the system has infinitely many solutions. If and denote the number of elements in and respectively, then

• (A)=2, =0Correct
• (B)=1, =0
• (C)=2, =2
• (D)=0, =2