A

To determine the relationship between the resistances of a wire at different temperatures, we use the temperature coefficient of resistance formula:
Step 1: The resistance at temperature $t$ is given by the formula:
$$R_t = R_0 (1 + \alpha t)$$
where:
- $R_t$ is the resistance at temperature $t$
- $R_0$ is the resistance at 0°C
- $\alpha$ is the temperature coefficient of resistance
- $t$ is the temperature in °C
Step 2: Analyzing the options provided, option A represents this relationship clearly. The other options either imply incorrect relationships or use incorrect formulations.
Therefore, option A is correct.