An ideal shelter for housing a temperature-measurement instrument should be:

White
Black
In the shade
Both white and in the shade E. Both black and in the shade

The correct answer is D. Both white and in the shade.

A white shelter reflects sunlight, which helps to keep the instrument cool. A shelter in the shade also helps to keep the instrument cool, as it is not directly exposed to the sun’s rays.

A black shelter would absorb sunlight, which would make the instrument warmer. A shelter in direct sunlight would also make the instrument warmer, as it would be directly exposed to the sun’s rays.

Therefore, the ideal shelter for housing a temperature-measurement instrument would be both white and in the shade.