To pay close attention while listening is the correct answer because listen carefully means to hear someone with focus and try to understand the message accurately.

In a classroom, this phrase is important when a teacher gives directions, explains a lesson, or asks students to follow steps.

Examples: Listen carefully while I explain the homework. The students listened carefully to the safety rules before the experiment.

The other choices are not exact meanings. To keep quiet all day is too broad, and to act in a calm way describes behavior, not focused listening.