Which of the following is an example of sound refraction?
a).sound waves bouncing off a canyon wall to create an echo
b).reverberations in a concert hall
c).a high pitch sound changing to a low pitch sound
d).sound waves changing direction as they encounter different air temperatures

Cold case files recently began re-investigating an old murder case. the murder took place in the park; a young man, james, was hit over the head with a brick and killed. police suspected the jealous former boyfriend of james' wife, karen. whoever killed james may have washed their hands in a near-by bird bath as detectives found blood in the bird bath. since the murder took place before dna fingerprinting was available, the suspected killer, ronnie, went free. detectives are now reviewing the blood evidence using dna fingerprinting. based on the dna fingerprints of all possible suspects, who is james' killer?