DNA quality

Which read(s): 1. contain either a SNP (a single nucleotide polymorphism) or a position where different members of a multi-gene family have a different base? C 2. doesn't have any DNA? B 3. is a PCR product? A, B, and C.  All of three reads were obtained by sequencing PCR products, generated with the same set of primers.The quality plots that I refer to are here.