In a triangle ABC if following relations hold good, in which of the case(s) the triangle is a right angled triangle?

A) r2 + r3 = r1 - r

B) a^2 + b^2 + c^2 = 8R^2

C) if the diameter of an excircle be equal to the perimeter of the triangle

D) 2R = r1 - r

Note: r - inradius

R - circumradius

1, 2 ,3 are subscripts denoting different inradiuses