Two methods are proposed to measure the effectiveness of a brand of sunscreen. Method A: Survey adults visiting a beach on a busy weekend. Ask each adult which brand of sunscreen they are using, and assess their arms for sun exposure.

Method B: Volunteers are randomly assigned to one of two brands of sunscreen. Each volunteer is asked to report back at the end of the day, and their arms are assessed for sun exposure.

Which statement is a correct interpretation of these methods?

Both methods are experiments because sun exposure is assessed in both methods.
Both methods are observational studies because neither method attempts to influence responses.
Method A is an experiment because it compares many brands of sunscreen, while method B is an observational study.
Method B is an experiment because it randomly assigns volunteers a sunscreen, while method A is an observational study.