The correct statement is: e) some are parasitic.
Explanation: Arthropods are a diverse group of invertebrates that include insects, crustaceans, and arachnids. While arachnids (such as spiders and scorpions) are a specific subgroup of arthropods, other arthropods like insects and crustaceans can also exhibit parasitic behavior. For example, certain species of lice and fleas are parasitic insects that feed on the blood of their hosts. This makes option e) the correct choice, as it highlights a characteristic that is true for at least some arthropods other than arachnids.