Read the given statements (Assertion and Reason) carefully and select the most appropriate option with respect to them.

Assertion (A): Trees grow against gravity.

Reason (R): Nature defies gravitational law.

Assertion (A): Trees grow against gravity.  (True)
Trees exhibit negative geotropism, meaning they grow upwards, opposite to the force of gravity.
Reason (R): Nature defies gravitational law.  (False)
Nature does not defy gravitational law; rather, plants have adapted mechanisms (like auxin hormone distribution) to grow against gravity.
Therefore, A is true, but R is false.
Thus, the correct option  is (d) A is true, but R is false.