Final answer:
The integer used to represent 3 degrees below zero is -3, as negative numbers indicate values below the zero mark in temperature scales and other contexts.
Step-by-step explanation:
The integer that would be used to represent 3 degrees below zero is -3. In temperature measurements, negative numbers are used to denote temperatures below the zero mark, such as -10 °F or -15 °C, which are colder than 0. Additionally, in physics, convention often assigns a negative sign to objects moving downward, reinforcing the idea that negative numbers can represent something beneath a baseline or 'zero' level. Therefore, the correct answer to the student's question is B. -3.