What data could most likely be accurately replicated by other scientists?
a) determining the health of a mouse based on it appearance
b) determining the distance between trees in steps
c) calculating the length of chicken eggs in millimeters
d) reporting the height of horses in hands

I don't think it's A. Think of all the different colors, ages, and unique predetermined ( by environment and genes) physical abilities of mice. Not to mention the fur, which would hinder any observations made off of the animals' skin (physical appearance). There would be plenty of data, but it would be inaccurate data. Just like measuring a horse in hands (when all hands are different sizes), or like determining the distance between trees in steps ( when everyone has varying lengths of stride). C is the correct answer, as it is the only data which can be replicated. ( If one scientist measures in millimeters, then another scientist will be able to get the same results.) 

Dna overload will occur

Except hold on to his or her beliefs even if there is no evidence for those beliefs.