Which of the following is the complete factorization of p2−4q2−r2+4qr−2p+1?
(p−1−2q+r)(p−1+2q−r)
(p−1−2q−r)(p−1+2q+r)
(p+1−2q+r)(p+1+2q−r)
(p−1)2−(2q+r)2
