Assertion. Coloured cations can be identified by borax bead test.
Reason. Transparent bead `(NaBO_(2) + B_(2)O_(3))` forms coloured bead with coloured cation.
A. If both assertion and reason are true, and reason is the true explanation of the assertion.
B. If both assertion and reason are true, but reason not is the true explanation of the assertion.
C. If assertion is true, but reason is false.
D. If both assertion and reason are false.