Answer:
b. a unique real solution
Explanation:
A quadratic equation ax² + bx + c = 0 ,
Has two distinct real roots,
If discriminant,

Has two equal real roots,
If D = 0,
Has two imaginary roots or no real roots,
if D < 1,
Here. the given qudratic equation,

By comparing,
a = 4, b = 32, c = 64,

Hence, the equation has two equal real roots or a unique real solution.
i.e. OPTION 'b' is correct.