A motion that is given an initial velocity and follows a path under the influence of gravity.   a. Rectilinear motion b. Uniform Circular motion  c. Projectile motion d. Plane motion

Please explain and give the final answer for this problem. I keep getting wrong answers after calculations.

1. Describe the motion of an object: a. if the direction of the acceleration is the same as the direction of motion of the object. b. if the direction of the acceleration is opposite to the direction of motion of the object.

When there is air resistance present how to the velocity and acceleration vectors behave?   a.The acceleration and velocity vectors are both constant magnitude but continually change direction.   b.The acceleration vector is constant and points straight down. The velocity vector is at a tangent to the trajectory   c.The acceleration vector is perpendicular to the trajectory and the velocity vector is at a tangent to it.   d.The acceleration changes throughout the flight with its x-component opposite the direction of motion. The velocity vector is at a tangent to the trajectory