A metal block with a temperature of 30°C is placed inside a bowl of water with a temperature of 45°C. Which of the following will occur when the metal block is placed inside the Bowl water?

The water will cool down

Explanation:

Both the water and the metal block will reach Thermal equilibrium which is a state where neither of them will be transferring energy (heat) to the other because they are now of the same temperature.  

For instance, if you put a cold can in water to warm it up, the water will keep reducing in temperature while the cold can increases in temperature until both the can and the water have the same temperature.

The same logic applies here. The metal block is cooler than the water so the water will cool down and the metal block will get more heat until both of them achieve a temperature somewhere between the temperatures that both the water and the block started off with.