Rust away is a new chemical agent designed to prevent rusting on metallic goods like bicycles, household sinks, and pipes. the manufacturer performs some tests to determine whether rust away does prevent rusting. the manufacturer puts 150 metallic plates into three groups of 50. the first group is left as it is. the second group receives a thin layer of rust away. the third group receives a thick layer of rust away. each plate is then exposed to conditions that have been designed to induce rusting. the level of rusting in each plate is recorded. the method of data collection in this situation is an: a) expirmentb) observational study