Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Melting point of Boron \( (2453 \, \text{K}) \) is unusually high in group \( 13 \) elements.
Reason (R): Solid Boron has very strong crystalline lattice.
In the light of the above statements, choose the most appropriate answer from the options given below :