Which are the oldest layers of rock? at bottom of strata

at top of strata

in middle of strata

2nd layer of strata

Its the bottom because its located in the bottom

Explanation:

a basic law of geochronology, stating that in any undisturbed sequence of rocks deposited in layers, the youngest layer is on top and the oldest on bottom, each layer being younger than the one beneath it and older than the one above it.

the second type of galaxy is called a barred spiral, which has a thing called a bar straddling the nucleus