Out of every 10 animals on earth, 7 are ____.

The correct answer is Option (4) → Insects

Option (4) Insects — Correct. Of the options, only insects are a large enough group: they alone make up 7 of every 10 animal species.

NCERT Extract:
Biodiversity – “… Let us look at some interesting aspects about earth’s biodiversity based on the currently available species inventories. More than 70 per cent of all the species recorded are animals, while plants (including algae, fungi, bryophytes, gymnosperms and angiosperms) comprise no more than 22 per cent of the total. Among animals, insects are the most species-rich taxonomic group, making up more than 70 per cent of the total. That means, out of every 10 animals on this planet, 7 are insects.”