Question

how does a pond form?
a mudflow blocks a river.
water collects in a low-lying area.
humans use a dam to create a reservoir.
a depression made by an ice sheet fills with water.

Explanation:

A pond forms when water collects in a low - lying area. A mudflow blocking a river would form a lake (a larger body of water than a pond). Humans using a dam to create a reservoir is a man - made structure (usually larger than a pond). A depression made by an ice sheet filling with water is more likely to form a glacial lake.

Answer:

C. Water collects in a low - lying area.