What is the noble gas notation (electron configuration) for the manganese atom?

Any element's electronic configuration reveals the atom's total number of electrons, which is equal to the element's atomic number. Any element's electronic configuration entails packing electrons into the s, p, d, and f orbitals. According to the Aufbau principle, which moves from the lower energy level to the higher energy level, electrons are filled into various orbitals. The term "noble gas notation" refers to the writing of a noble gas in the electron configuration of any element. The electrons in any atom at a lower energy level are covered by the atomic number of the noble gas.

The atomic number of manganese is Z=25, and the nearest Noble gas is argon, Z=18.

And so we do not have to specify the configuration of the first 18 electrons, because these approximate the configuration of argon.

$\mathrm{Z}=18,1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{s}}^6$

For manganese, Z=25

$\mathrm{Z}=25,1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{s}}^{6}4{\mathrm{s}}^{2}3{\mathrm{d}}^5$

Therefore the electronic configuration of Mn≡$\left[\mathrm{Ar}\right]4{\mathrm{s}}^{2}3{\mathrm{d}}^5$

Hence, the correct option is (A).