An exothermic process releases heat, and causes the temperature of the immediate surroundings to rise. An endothermic process absorbs heat and cools the surroundings.
The ? is poorly worded because the lab (a room) will release heat to the outside (of the room) if areas adjacent to the room are cooler than the room: an exothermic process. If we are conducting an experiment IN a lab (a room) and the room temp. drops, then the EXPERIMENT must be the source of an endothermic process because it has absorbed some heat that used to be in the room. Example: a big pile of dry ice dumped in the room will lower the temperature of the room---an endothermic process. If instead, we measure the temperature of the room after several dozen students leave the room, the temperature will drop because several dozen "exothermic processors" have left the room.
So, if the ? was intentionally worded this way, then the answer is 'EXO.'- because the room has released some of its heat to the surroundings.