The broadly utilitarian argument says that -

The correct answer is Option (2) → Biodiversity plays a major role in many ecosystem services that nature provides.

NCERT groups the reasons for conserving biodiversity into three kinds: narrowly utilitarian, broadly utilitarian and ethical. The narrowly utilitarian argument is about direct products such as food, fibre, firewood and medicines.

Option (1) Biodiversity plays no role in many ecosystem services that nature provides. — Incorrect. This is the opposite of the argument. Services such as oxygen production and pollination come from living organisms.

Option (2) Biodiversity plays a major role in many ecosystem services that nature provides. — Correct. The broadly utilitarian argument looks at the indirect benefits of biodiversity. These services are not sold in a market like food or medicines, yet our life depends on them.

Option (3) Biodiversity plays a minimum role in many ecosystem services that nature provides. — Incorrect. The argument says the role is major, not minimum. Without these services, life on earth would be hard to carry on.

Option (4) Conserving biodiversity is not obvious. — Incorrect. This is not an argument for conservation at all. NCERT says some reasons for conserving biodiversity are obvious and some are not so obvious, but all are equally important.

NCERT Extract:
Why Should We Conserve Biodiversity? – “… The broadly utilitarian argument says that biodiversity plays a major role in many ecosystem services that nature provides. The fast-dwindling Amazon forest is estimated to produce, through photosynthesis, 20 per cent of the total oxygen in the earth’s atmosphere. … You can get some idea by finding out how much your neighborhood hospital spends on a cylinder of oxygen. Pollination (without which plants cannot give us fruits or seeds) is another service, ecosystems provide through pollinators layer – bees, bumblebees, birds and bats.”