You perform a PCR using a set of primers (both are 20- mers) that you have designed yourself using gene sequence data. Electrophoresis shows not the predicted 750 bp fragment amplicon, but a large amount of 30 bp product. What happened?

A. You used the wrong gene sequence in the analysis and design of the primers.
B. The wrong annealing temperature was used resulting in aberrant amplification.
C. The primers have a 10 bp homology at the 3' end, causing them to anneal together instead of with the genomic DNA.
D. The wrong extension temperature was used.