The Assertion states that the first ionization energy of Beryllium (Be) is greater than that of Boron (B). To analyze this, let's consider the electronic configurations and other factors influencing ionization energies. Beryllium (Be) has an electronic configuration of $$1s^2 2s^2$$, while Boron (B) has an electronic configuration of $$1s^2 2s^2 2p^1$$. The first ionization energy refers to the energy required to remove the most loosely held electron from an atom's outer shell. In Beryllium, this electron is removed from a completely filled $$2s$$ orbital, which is a stable state. In Boron, the electron to be removed is from a $$2p$$ orbital, where only one electron is present, and the $$2p$$ orbital is an in-progress shell filling after the $$2s$$ is filled.

The stability associated with Beryllium's filled $$2s$$ orbital typically results in a higher ionization energy compared to Boron, which has an uncompleted subshell with a loosely held $$2p$$ electron. Thus, it is generally easier (less energy required) to remove an electron from the $$2p$$ orbital of Boron than to remove one from the filled $$2s$$ orbital of Beryllium, confirming that the Assertion is correct.

The Reason provided states, "2p orbital is lower in energy than 2s." However, this statement is not precise or accurately phrased in the context of atomic orbital theory. In actuality, in multi-electron atoms, the $$2s$$ orbital is generally lower in energy than the $$2p$$ orbital. The given Reason seems to imply the opposite, thereby making the Reason incorrect.

Therefore, the appropriate answer here is:

Option C: If assertion is CORRECT, but reason is INCORRECT.