Answer
(b) exactly c
Work Step by Step
The space probe is moving with velocity (0.2c). The speed of light is c. As the sunlight passes the probe, the light and the probe are travelling in the same direction.
Then as per classical relativity, the speed of light measured by the probe would be $c-0.2c=0.8c$
But actually the value of the speed of light is same in all inertial frames. So the probe would measure the speed of light to be exactly c.
