This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to safely burn candles
Place the candle in a well ventilated room.
There should be at least 3 ft (910 mm) between the candle flame and the surface above it. If burning multiple candles, place them at least 3 in (76 mm) apart from each other.

Choices:
(a). They should be evenly spaced, with the candles facing each other at roughly equal angles. Candles are not flammable unless they are made from wood, not glass..
(b). This prevents them from blowing out and making a fire. Place a piece of cheesecloth over the candles..
(c). This will minimize the risk of flammable water separating between both candle holders. The ideal amount of space between the wax and flame will depend on the size of the candle..
(d). This prevents the candles from creating their own drafts. Remove your candle from anything flammable..
The answer is:
(d).