The correct answer is option D. are flawed.
The experiments, which are given by a scientist for peer review or as a claim, must be replicatable. the replication of the experiment helps in the removal of any biases and determines the accuracy of the experiment.
In case, the experiments are not able to be repeated or replicated then they must have some flaws. Presence or absence of the control does not determines its accuracy, it only helps in the comparison of the result obtained.