The structure of $2‐$methoxy$‐2‐$methylpropane is

The IUPAC name of the following compound is:

The structural formula for $2-$ethylprop$-2-$en$-1-$ol is:

The IUPAC name of the above compound is 

$\mathrm{A}.$ ${\left({\mathrm{CH}}_3\right)}_3\mathrm{C}—\mathrm{OH}$

$\mathrm{B}.$ ${\left({\mathrm{CH}}_3\right)}_3\mathrm{C}—{\mathrm{NH}}_2$

Which of the two is the correct statement with respect to the above structures?

The correct IUPAC name of the following compound is: