Final answer:
A turbidity current is an underwater current created by gravity-driven flow of sediment down a slope, resulting in sedimentary formations known as turbidites. The correct answer from the given options is '(e) none of the above' because none of the options accurately describes a turbidity current.
Step-by-step explanation:
A turbidity current is a type of underwater current that is primarily influenced by gravity and carries sediment down a slope on the sea floor. This phenomenon occurs when sediment or silt on the slope becomes dislodged, often due to an earthquake or another disturbance, and this material begins to move downslope thanks to the pull of gravity. As the sediment moves, it picks up more material, resulting in a current that can transport material over great distances.
The sedimentary deposits formed by these currents are known as turbidites. The currents have the capability to sort grains by density, leaving characteristic sedimentary structures such as flute casts, which can indicate the direction of flow. These currents are often associated with catastrophic slope failures and are not related to the methods described in options (b) through (d) of the multiple-choice question.
Considering the given options and the reference material provided, the correct answer to the question would be '(e) none of the above' as no option accurately describes a turbidity current.