The correct answer is option 'C' - 3d14s2. Let's understand why this is the correct answer.

1. Introduction:
Before we delve into the electronic configuration of scandium, let's first understand the concept of filling orbitals. Electrons occupy different energy levels in an atom, represented by different orbitals. These orbitals are filled in a specific order, following the Aufbau principle.

2. Aufbau Principle:
According to the Aufbau principle, electrons fill the lowest energy orbitals first. The order of filling orbitals is as follows: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, and so on. The energy levels of the orbitals increase as we move from left to right in the periodic table.

3. Filling of 4p Orbital:
Before the 4p orbital is filled, the 3d orbitals become energetically favorable to fill. This means that the 3d orbitals have a lower energy than the 4p orbital. Hence, electrons start filling the 3d orbitals before filling the 4p orbital.

4. 3d Transition Series:
The elements in the 3d transition series start from scandium (Z = 21). Scandium is the first element in the transition series, and its electronic configuration determines the pattern for the rest of the series.

5. Electronic Configuration of Scandium:
The atomic number of scandium is 21, which means it has 21 electrons. To determine its electronic configuration, we need to follow the Aufbau principle and fill the orbitals in the correct order.

- The first two electrons fill the 1s orbital.
- The next two electrons fill the 2s orbital.
- The next six electrons fill the 2p orbital.
- The next two electrons fill the 3s orbital.
- Now, we come to the 3d and 4s orbitals. Since the 3d orbitals become energetically favorable before the 4p orbital, we fill the 3d orbitals before the 4s orbital.
- The 3d orbitals can hold a maximum of 10 electrons. So, we fill all 10 electrons in the 3d orbitals.
- Finally, the remaining electrons (1) fill the 4s orbital.

Thus, the electronic configuration of scandium (Z = 21) is 3d14s2. This configuration follows the principle of filling the lower energy orbitals before the higher energy ones.

In conclusion, the correct answer is option 'C' - 3d14s2, which represents the electronic configuration of scandium.