which layer is the oldest, which is the youngest?

Layer D, is the oldest layer because layer's A and e are on top of it. Layer E's the second oldest and layer A is the third oldest because the same rock composition of layer B is above it, Then next is layer B and the youngest of all the layer's is C.

The unconformities are the squigly lines between layer's A and B, also at the very top of B due to erosion (weathering)