Which of the following was not the reason for the rise of Magadha as the most powerful Mahajanapada?

Policies of Hoysala rulers.

The correct answer is Option (4) → Policies of Hoysala rulers.

1) A region with productive agriculture. True – Fertile Gangetic plains gave surplus produce.

(2) Accessibility to iron mines provided resources for tools and weapons. True – Magadha had access to iron ore in present-day Jharkhand.

(3) Elephants for army were found in the forests of the region.  True – Elephants were a major military resource.

(4) Policies of Hoysala rulers. Not true – The Hoysalas ruled much later (12th–14th century CE in Karnataka), long after the time of the Mahajanapadas.