Accretion is defined as: a. gravity that pushes matter in a circular manner into an outer source. b. the disk of material surrounding a black hole. c. gravity that pulls matter inward in a spiraling matter. d. none of the above.

C. Gravity that pulls matter inward in a spiraling matter.

Explanation:

In astrophysics, particles are pulled towards a massive object due to gravity which further attracts more particles. A disk of particles is formed around the object. Hence, we can define Accretion as a process in which particles are accumulated in a form of a disk of surrounding a massive object (like a black-hole) due to gravity which pulls the matter inwards and matter spirals around the massive object. Galaxies, planets etc. are formed out of accretion process. Thus, the correct option is C.

this a false

explanation:

truck y has a greater velocity than truck x.