Which of the Following Teachers Is Utilizing Discovery Learning

Which of the following teachers is utilizing discovery learning?

A) Mr. Doolittle's class is busy working with paints of the primary colors. Students are excited because they have just figured out how to make green paint.
B) Ms. Rowley has her students at the edge of their seats. While she has an important academic concept to communicate, she has been asking them very perplexing questions and they are excited to see where she is going with her efforts.
C) Mr. MacNeil's class is thoroughly engaged with newspapers, magazines, and the Internet trying to answer the teacher's question about how we should go about raising funds to allow for more computers in their school.
D) While Mr. Whitehead also watches students work with their paints, he offers suggestions that might aid them in reaching the objective of the activity, to understand yellow and blue makes green.