A.Chitinous exoskeleton, three body segments notochord and one pair of antennae
B.Chitinous exoskeleton, ventral nerve cord, several body segments and two pairs of antennae
C.Chitinous exoskeleton, ventral nerve cord, three body segments and two pairs of antennae
D.Chitinous exoskeleton, ventral nerve cord, several body segments and one pair of antennae