Use the Following Information to Answer the Question

Multiple Choice

Use the following information to answer the question. Which treatment is most effective at treating head lice: Benzyl alcohol lotion, dandruff shampoo, or mayonnaise? In a study, researchers randomly assigned 55 subjects with head lice to one of three groups. All subjects had similar cases of head lice. Depending on which group they were assigned to, subjects received an over- the- counter remedy of Benzyl alcohol lotion, dandruff shampoo, or mayonnaise, which was applied by a trained professional. Afterwards, each subject was examined and any lice or eggs found were counted. Researchers found that Benzyl alcohol lotion produced better results than both dandruff shampoo and mayonnaise.
-Was this an observational study or a controlled experiment?

A) Observational Study
B) Controlled Experiment