Which type of unconformity exists between parallel layers of sedimentary rock?
a. disconformity
b. nonconformity
c. angular unconformity

The correct answer to the question: Which type of unconformity exists between parallel layers of sedimentary rock, would be, A: Disconformity.

Explanation:

In general, when talking about geologic positioning of rocky layers, and sediment, we talk about how these layers were formed throughout time, and, if there is discontinuation of the sequence in which the layers should have been formed. Geologists then study these divergences in rock-layer formation and have found that there are several types, affected mostly by erosion and inconsistencies in rock deposition, which might come to divide, or affect the continuity of layers, or strata, of different ages. This is called unconformity. Discomformity is precisely a type of unconformity in which there is a discontinuation of the expected deposition of rock between two layers of different ages, and it happens between parallel layers of sedimentary rock. This is why the answer is A.