In the Selective Repeat Automatic Repeat Request protocol if the receiver window as shown receives frames $2$ and $3$ waiting for frame $1$ what will the receiver do:

a$.$ Deliver the frames $2$ and $3$ to the upper layer only if received frame $4$ or frame $1$

b$.$ Deliver all frames to the upper layer only if all frames in the window are received.

c$.$ Deliver the frames $2$ and $3$ to the upper layer only if received frame $1.$

d$.$ Deliver the frames $2$ and $3$ to the upper layer

e$.$ Deliver the frames $2$ and $3$ to the upper layer only if received frame $4$