3.13 x 10 ^9
This is because only 1 number is front of the decimal and 2 numbers should be after
single-nucleotide polymorphism, I think this might be it. I hope it helps.
Remember that a controlled variable is a variable that stays the same thoughout the experiment.
it wouldn't be a. because two different wires were used
the final length of the wax would be your dependent variable, so it wouldn't be c.
the thermal conductivity is the independent variable so it isn't d.
the original length of the wax was the same for both.
So B is your answer.
The answer is the letter C i think