What’s the answer to 15 please please help me

Idon’t quite understand this problem

Suppose a comet has an orbital period of 309.1 years around the sun. what is it’s average distance from the sun?

Which of the following situations is impossible? a) an object has velocity directed east and acceleration directed east. b) an object has zero velocity but non-zero acceleration. c) an object has constant non-zero velocity and changing acceleration. d) an object has velocity directed east and acceleration directed west. e) an object has constant non-zero acceleration and changing velocity.