The force that moves sediment in a landslide or mudflow is

gravity

Explanation:

Weathering is a process that breaks down rocks and other materials on the earth's surface producing 'sediments'. Movement of these sediments from one place to another is called erosion. They can be transported in different ways; through water, ice, wind or by gravity. In landslides or mudflows, sediments generally move downhill and get transported naturally under the influence of the gravitational force. Hence, The force that moves sediment in a landslide or mudflow is gravity.

sorry i was late, but i don't know what assignment your talking about, i'm in flvs as well, im in earth space science. but u are behind pace bc every class should be in the 3's or 4'

the answer is a! (2.9 x 10^-18 j) hope i could someone. : )