Question 1 all of the following are possible sources of error in a scientific investigation except for a. manipulating the wrong variables in the experiment. b. completing only one trial in the experiment. c. measuring the change in temperature incorrectly. d. reviewing previously published studies before the experiment.

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?