Final answer:
The correct term to use is 'feet' as in 'An elephant is four feet' because elephants have multiple feet. In subjects like physics or biology, this question could relate to the pressure exerted by an elephant's feet due to its weight.
Step-by-step explanation:
The correct word to complete the sentence "An elephant is four feet / foot." is "feet." The plural form of foot is used because elephants have multiple feet.
In the context of physics or biology, when considering the pressure exerted by an elephant's foot, which would involve the weight of the elephant and the area of its footprint, we understand that on average a large African elephant can weigh up to 7 tons and has a footprint area of 250 in², resulting in about 14 lb/in² of pressure per elephant foot.