Assertion and Reason.
Assertion (A) : Burning of wood log to charcoal is a physical change.
Reason (R) : The products formed of burning a piece of wood can be easily converted back to wood log.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.