Question

place the following units in order, from smallest to largest.
a epoch, period, eon
b eon, epoch, period
c period, eon, epoch
d epoch, eon, period

Explanation:

In geological time scales, an epoch is a smaller unit, a period is larger than an epoch, and an eon is the largest. So the order from smallest to largest is epoch, period, eon.

Answer:

A. Epoch, period, eon