A first-grade class has completed a unit on animal life cycles. Which of the following is the most effective way for a teacher to assess the students' understanding of the unit concepts?

a) Having students write an essay explaining the life cycle of a specific animal.
b) Administering a multiple-choice test on various animal life cycles.
c) Observing and discussing student-created drawings depicting different animal life stages.
d) Conducting individual interviews with students to ask about their understanding of animal life cycles.