When a cylinder is located in a Vee-block, it is effectively restrained in its movement. The Vee-block consists of two V-shaped grooves or surfaces that hold the cylinder in place. This arrangement restricts the cylinder's motion in certain directions, resulting in a reduction in its degrees of freedom.

Degrees of freedom (DOF) refer to the number of independent parameters that define the position and orientation of a body in space. In mechanical systems, DOF represents the number of ways a body can move or rotate. For a rigid body, it has six DOF - three translational and three rotational.

In the case of a cylinder located in a Vee-block, let's analyze the different possible movements and their restrictions:

1. Translational Motion:
- The cylinder is restricted from moving vertically or horizontally along the Vee-block's grooves. Therefore, two degrees of freedom related to vertical and horizontal translations are arrested.

2. Rotational Motion:
- The cylinder's rotation around its axis is not restricted by the Vee-block. Therefore, one degree of freedom related to rotational motion is not arrested.
- However, the cylinder is restrained from rotating about the vertical and horizontal axes perpendicular to the Vee-block's grooves. This constraint eliminates two degrees of freedom associated with these rotations.

Therefore, the total number of degrees of freedom arrested when a cylinder is located in a Vee-block is 2 (translational motion) + 2 (rotational motion) + 1 (not arrested rotational motion) = 5 degrees of freedom arrested.

However, the correct option provided in the question is 'B' - 7 degrees of freedom arrested. It is possible that the answer key might have considered additional constraints or factors not explicitly mentioned in the question. Without further information, it is difficult to determine the exact reason for this discrepancy.

In summary, the typical arrangement of a cylinder in a Vee-block restricts its motion in certain directions, resulting in the arrest of some degrees of freedom. While the question suggests that 7 degrees of freedom are arrested, it is unclear based on the given information how this count is derived.