Because the basic body parts present in the adult are also present in the infant at birth.
Explanation
Metamorphosis is a biological process involving a conspicuous and abrupt change in an animal's body structure after birth or hatching. It is commonly observed in insects (e.g., caterpillar to butterfly) and amphibians (e.g., tadpole to frog), where the larval stage looks completely different from the adult stage.
In contrast, humans undergo direct development. This means that the offspring is born resembling the adult in terms of general body structure and organ systems.
- Because humans do not lay eggs. is incorrect: The method of reproduction (oviparity vs. viviparity) does not define metamorphosis. For example, birds and reptiles lay eggs but do not undergo metamorphosis; their hatchlings resemble the adults.
- Because the basic body parts present in the adult are also present in the infant at birth. is correct: The primary reason human development is not classified as metamorphosis is that the human infant possesses the same basic body parts (head, limbs, torso) and anatomical arrangement as the adult at the time of birth. The development process involves growth and maturation rather than a fundamental transformation of the body plan.
- Because humans develop inside the uterus. is incorrect: While humans are viviparous (developing inside the uterus), this is a characteristic of mammals, not the defining factor for the absence of metamorphosis.
- Because human growth is a slow process. is incorrect: The speed of growth is not a criterion for distinguishing between metamorphosis and direct development.
Key Takeaway: Metamorphosis implies a drastic transformation of the body structure (indirect development), whereas human development is characterized by growth where the infant structurally resembles the adult (direct development).