Assertion (A): The IUPAC name of the compound ${\mathrm{CH}}_3\mathrm{CH}\left(\mathrm{OH}\right)-\mathrm{CH}\left({\mathrm{NH}}_2\right){\mathrm{CH}}_3$ is 3-amino butan-2-ol
Reason (R): $N{H}_2$ Group is not the main functional group.
Choose the correct statement 

Both (A) and (R) are correct and (R) is the correct explanation of (A)

(A) is correct but (R) is not correct

Both (A) and (R) are correct but (R) is not the correct explanation (A)

(A) is not correct but (R) is correct