The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
The roots of a quadratic equation are complex conjugates (p+iq,p−iq) only if the coefficients, i.e. a, b, c are real.
If a2+b2+c2<0, it implies that at least one of a, b, c are imaginary (since minimum value of a perfect square of a real number is zero).
Since one of a, b, c are imaginary, the roots of the quadratic will not be complex conjugates of one another.
Hence, (A) is correct.