Question

which statement explains one reason why unconformities occur?
rocks along a fault break and move
igneous rock forms at earths surface
no sediment is deposited over a long time
igneous rock forms between sedimentary layers

Explanation:

Unconformities occur when there is a gap in the geological record. This can happen if no sediment is deposited over a long time, creating a break in the sequence of rock layers.

Answer:

No sediment is deposited over a long time.