A
Below is a question with multiple-choice answers. Choose the correct option based on your reasoning.

### Question:
In a lab investigation, a student notes that two metal blocks have the same mass. Based on this observation, if the two blocks were put on opposite sides of a balance, they would best represent

### Choices:
A. balanced forces.
B. unbalanced forces.
C. equal and opposite reactions.
D. objects in motion.

### Answer:
