The correct answer is: C. Circle and straight line
The body centrode is the path traced by the center of mass of a rolling body. The space centrode is the path traced by a point on the body that is always in contact with the ground.
When a circular wheel rolls on a straight track, the body centrode is a circle. This is because the center of mass of the wheel always stays in the same place relative to the wheel. The space centrode is a straight line. This is because the point of contact between the wheel and the ground always stays in the same place relative to the ground.
Here is a diagram that illustrates the motion of the body centrode and the space centrode:
[Diagram of a wheel rolling on a straight track, with the body centrode shown as a circle and the space centrode shown as a straight line.]
The body centrode is shown as a circle because the center of mass of the wheel always stays in the same place relative to the wheel. The space centrode is shown as a straight line because the point of contact between the wheel and the ground always stays in the same place relative to the ground.
I hope this explanation is helpful!