To solve this problem, we need to identify which feature is not present in Periplaneta americana (the American cockroach). Let's analyze each option:$\newline \bullet$Option 1: Schizocoelom as body cavity.$\newline$ - Schizocoelom is a type of body cavity formation found in protostomes, which includes arthropods like cockroaches.$\newline$ - Therefore, this feature is present in Periplaneta americana.$\newline \bullet$Option 2: Indeterminate and radial cleavage during embryonic development.$\newline$ - Indeterminate and radial cleavage are characteristics of deuterostomes, not protostomes.$\newline$ - Cockroaches, being protostomes, do not exhibit this type of cleavage.$\newline$ - Therefore, this feature is not present in Periplaneta americana.$\newline \bullet$Option 3: Exoskeleton composed of N-acetylglucosamine.$\newline$ - The exoskeleton of arthropods, including cockroaches, is made of chitin, which is a polymer of N-acetylglucosamine.$\newline$ - Therefore, this feature is present in Periplaneta americana.$\newline \bullet$Option 4: Metamerically segmented body.$\newline$ - Metamerism, or segmentation, is a characteristic of arthropods, including cockroaches.$\newline$ - Therefore, this feature is present in Periplaneta americana.$\newline$Based on the analysis, the feature that is not present in Periplaneta americana is Option 2: Indeterminate and radial cleavage during embryonic development.$\newline$However, the correct option provided is Option 3, which seems to be a mistake in the question since the exoskeleton composed of N-acetylglucosamine is indeed present in cockroaches.