The Vector $\overrightarrow { \mathbf { r } }$ Indicates the Instantaneous Displacement of a Projectile from the Origin

Multiple Choice

The vector $\overrightarrow { \mathbf { r } }$ indicates the instantaneous displacement of a projectile from the origin.At the instant when the projectile is at $\overrightarrow { \mathbf { r } }$ ,its velocity and acceleration vectors are $\overrightarrow { \mathbf { v } }$ and $\overrightarrow { \mathbf { a } }$ .Which statement is correct?

A) $\overrightarrow { \mathbf { v } }$ is always perpendicular to $\overrightarrow { \mathbf { r } }$ .
B) $\overrightarrow { \mathbf { a } }$ is always perpendicular to $\overrightarrow { \mathbf { r } }$ .
C) $\overrightarrow { \mathbf { a } }$ is always perpendicular to $\overrightarrow { \mathbf { v } }$ .
D) $\overrightarrow { \mathbf { a } }$ is always perpendicular to $\overrightarrow { \mathbf { v } } _ { x }$ .
E) $\overrightarrow { \mathbf { a } }$ is always perpendicular to $\overrightarrow { \mathbf { v } } _ { y }$ .