The correct response is:
After some time passes, the substances will reach the same temperature.
When substance A (at 50°C) is dropped into substance B (at 25°C), heat will flow from the hotter substance (A) to the cooler substance (B) until thermal equilibrium is reached, meaning both substances will eventually reach the same temperature somewhere between 25°C and 50°C, depending on their masses and specific heat capacities.