Assertion. Graphite is a good conductkor of heat and electricity.
Reason. Graphite has all the electrons firmly held in C-C, `sigma`-bonds.
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.