The four quantum numbers for the electron in the outer most orbital...

The set of numbers used to describe the position and energy of the electron in an atom are called quantum numbers. There are four quantum numbers, namely, principal, azimuthal, magnetic and spin quantum numbers.

Electronic configuration of $K$ is:

$K = Atomicnumber = 191{s}^{2}2{s}^{2}2{p}^{6}3{s}^{2}3{p}^{6}4{s}^{1}$

The outermost electron is in $4{s}^{1}$

∴ $n = 4, l = 0, m = 0, s = + \dfrac{1}{2}$

Hence, the answer is option B.