Gustavo watched a cooking show on television demonstrating how to make chicken parmesan. even though he had never made chicken parmesan, he could then explain to a friend how to make it. gustavo's knowledge of cooking chicken parmesan is best explained by

Gustavo’s knowledge of cooking chicken parmesan is best explained by observational learning. This type of learning occurs when the person is gaining knowledge or skills with the use of having to look or observe the specific occurrence in front of him or her such as having Gustavo watch the cooking show that led him to know how to do it.

i would say b. research typically uses a variety of sources

rain should be the answer.