Given - a and b belong to set {1, 2, 3, 4}.

ax^2+bx+1=0.

To have real roots,

b^2 >=4.a.

If b = 4, then 'a' can be 1, 2, 3, 4 ( 4 possibilities )

If b = 3, then 'a' can be 1, 2. ( 2 possibilities )

If b = 2, then 'a' can be 1 (1 possibility)

If b = 1, then no value of a. ( 0 possibility)

Ans- B. 7