Final answer:
Moving left on the number line represents a decrease in temperature. Adding a positive integer means moving to the right on the number line.
Step-by-step explanation:
Moving left on the number line represents a decrease in temperature. Therefore, if the temperature increases by 2 degrees, it would mean moving to the right on the number line. In this case, the temperature would decrease. So, option a) is incorrect.
In mathematics, the symbol '+' represents addition. So, option b) is correct as adding a positive integer would mean moving to the right on the number line, resulting in an increase.
Adding a positive integer to a number line does not correspond to temperature. Therefore, option c) is incorrect.