Because product is bi-quadratic and one factor is quadratic so other factor must be quadratic
Other factor is of the form $x^2+ax+b$
So we get
$(x^2+2x+5)(x^2+ax+b) = = x^4 + (2+a)x^3 + (b+2a+5)x^2 + (2b+5a)x + 5b$
Comparing with $x^4+px^2+ q$ we get a = - 2 (coefficient $x^3$) and $b = 5$ from coefficient of x
So q = 5b = 25
Comparing coefficient of x^2 we get p = 5 -4 + 5 = 6
So Ans is (D) 6,25
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