4. which of the five classes of arthropods is the most diverse? explain.

Insecta or Hexapoda (insects) is the most diverse class. There are about 900,000 known insect species, three times as many as all other animal species together, and thousands of new ones are described each year. They are commonly grouped in 27 to 32 orders, depending upon the classification used. The largest order is that of the beetles (Coleoptera). Next, in order of size, are the moths and butterflies (Lepidoptera); the wasps , ants , and bees (Hymenoptera); and the flies and mosquitoes (Diptera). Other major orders are the true bugs (Hemiptera); the cicadas , aphids , and scale insects (Homoptera); the grasshoppers and crickets (Orthoptera); the cockroaches (Blattodea); and the mantids (Mantodea). 

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Ithink the answer is d.