Q: Fact 1: Arthropods are the largest phylum of invertebrates. Fact 2: Invertebrates are animals without a backbone. Given the two facts above, arthropods are the what without a backbone?

(I) largest phylum.
(II) graptolites.
(III) insects.
(IV) largest mammals.
(V) largest organs.
(VI) solid, liquid, gas.
(VII) animals.
(VIII) largest species.
A:
(I)