In which example would you be correct in describing an object in motion while your friend would also be correct in describing that same object as being at rest?

a$.)$ You are driving a car toward the east and your friend drives past you in the opposite direction with the same speed. In your frame of reference, you will be in motion. In your friend$$s frame of reference, you will be at rest.

b$.)$ You are driving a car toward the east and your friend is standing at the bus stop. In your frame of reference, you will be in motion. In your friend$$s frame of reference, you will be at rest.

c$.)$ You are driving a car toward the east and your friend is standing at the bus stop. In your frame of reference, your friend will be moving toward the west. In your friend$$s frame of reference, he will be at rest.

d$.)$ You are driving a car toward the east and your friend is standing at the bus stop. In your frame of reference, your friend will be moving toward the east. In your friend$$s frame of reference, he will be at rest.