Given the stream of consciousness rationale, provide a reasonable question and answer. Rationale: I got 20/(sqr2 +1) and just forgot to multiply by (sqr2 -1).
 The question and answer:
Consider a quarter of a circle of radius 20. Let r be the radius of the circle inscribed in this quarter of a circle. Find r.
Options:
(A) 20*(sqr2 -1) 
(B) 8*(sqr3 -1) 
(C) 4*(sqr7 - 1) 
(D) 12* (sqr7 -1) 
(E) None of these
The answer is (A)