Two Similar Drugs (Drug a and Drug B) to Alleviate

Two similar drugs (drug A and drug B) to alleviate back pain were released simultaneously.An investigator decides to test which of the drugs works better.He decides to conduct a trial in which randomly,half of the participants receive drug A for a month while the other half received drug B.After 2 weeks without any medication,participants switch the drug they were receiving (those who received A start taking B,and those who received B start taking A) .What type of study design was illustrated in this example?

A) Cross-sectional study
B) Factorial randomized clinical trial
C) Crossover randomized clinical trial
D) Crossover cohort study
E) Phase II clinical trial