In an experiment looking at the effect of cold on performance of the same task, participants were randomly assigned to spend 22 minutes in a cold room painted blue or 22 minutes in a room that was a comfortable temperature (72 F = 22.2 C) painted yellow. If counfounded, this experiment is most likely confounded by .

Color of the room

Explanation:

During experimental research, the presence of certain variables which may be likened to a third or extra variable in our experiment or correlation analysis. Usually this variable may result in causing an association which isn't wanted in the study at the time.

The difference in color of room will likely introduce a bias in our measurement. Since the effect of temperature is what is to be measured, only the temperature variable should be varied and all other available variables made the same. The room color in this experiment should be either yellow or blue for both rooms in other to avoid the effect of a confounder.

d - failures.

the only attempted british colony in north america before 1600 was roanoke, virginia, which was a total failure. england claimed several areas, including newfoundland, but made no sustainable attempts to colonize them before 1600.