What is a unit vector? A) a vector with all three directions or
dimensions (x, y and z or i, j, k) that are given
B) a vector with only one dimension
C) a vector that has an x and y components that
D) are equal in magnitude
a vector with a magnitude of one

A unit vector is (D) a vector with a magnitude of one

Explanation:

Unit Vector Information:

A unit vector is a vector with a magnitude of one. Vectors of different magnitudes can be scaled off the unit vector. Also, they can be used in two, three, or more dimensions.

Other Answers:

A. a vector with all three directions or  dimensions that are given

This is the definition of a 3D vector. This is a line segment in three-dimensional space running from point A (tail) to point B (head). Each vector has a magnitude (or length) and direction.

B. a vector with only one dimension

This is the definition of an one-dimensional vector. This type of vector has no dimension, but a number of components, therefore it behaves like a real number.

C. a vector that has an x and y components that  are equal in magnitude

(Unsure, I believe this would be defined as an equal vector. Correct me if I'm wrong and I will edit it.)

I hope this helps!

compass can be used day and night, cloudy or sunny