The most important advantage of experiments over observational studies is that

(a) experiments are usually easier to carry out.

(b) experiments can give better evidence of causation.

(c) confounding cannot happen in experiments.

(d) an observational study cannot have a response variable.

(e) observational studies cannot use random samples.

Treatment is applied to the subjects to observe their responses.

The random assignment method assigns subjects to treatments based on chance. Before the treatments are applied, random assignment establishes treatment groups that are comparable (except for chance variance). In experiments, randomization and comparison combined prevent bias or systematic favoritism.

Treatment is given to the individuals in an experimental study to see how they respond. It is founded on the concept of cause and effect. An observational study, on the other hand, is one in which the researcher observes the subject's reactions without imposing any conditions on them. As a result, an experimental investigation can yield a causal finding.

As a result, the best solution is (b).