Which part of experimental design is most important to a scientist when replicating an experiment?
(a) having exactly the same data as the previous experiment
(b) using the same procedure and variables as the previous experiment
(c) conducting and experiment similar to the previous experiment
(d) using the same laboratory that was used in the previous experiment.

(b) using the same procedure and variables as the previous experiment

Explanation:

(a) having exactly the same data as the previous experiment

Errors may exists so the data should be in the error margin of the experiment. Moreover, you may obtain totally different results and this could mean many things: the first experiment is faulty, the second one is faulty or may the premise in wrong and so on...  the same data as the previous experiment is not the most important thing.

(b) using the same procedure and variables as the previous experiment

You have to ensure that the procedure and the variables are the same with the previous experiment to be able in the end to compare the same thing. This is the most important thing when you replicating an experiment.

(c) conducting and experiment similar to the previous experiment

The experiment should be as close as possible to the previous one not "similar" because little things may have great impact on the final results.

(d) using the same laboratory that was used in the previous experiment.

If you maintain the same procedure and variables it does not matter the laboratory where you carry out the experiment.

it is the most commonly accepted one