Answer:
Option c
Explanation:
We are being asked to find unit vector u given the direction as x = < 40, 9 >. In most cases it would be v = < 40, 9 >, but it is the same concept.
To find the magnitude, given 40 and 9, you would do the following -

We got the magnitude to be 41. Now let us find unit vector u through the following calculations -

And there you have it! The solution is option c!