Since the zoo has more animals than enclosures, and every animal lives in an enclosure, it must be true that at least one of the enclosures contains more than one animal.
The argument above exhibits a pattern of reasoning that is most closely paralleled by which one of the following?The argument uses a simple counting principle: if there are more items than containers, and every item is placed in a container, then at least one container must hold more than one item.
More animals than enclosures means at least one enclosure has
multiple animals.
(A) Every person has two biological parents, so some people who have no brothers or sisters have more parents than their parents have children.
Wrong. This does not use the same “more items than containers” structure.
(B) Since every year there are more marriages than divorces, there must be some marriages that will not end in divorce.
Wrong. This compares events over time, not items assigned to fewer containers.
(C) Since boys under ten slightly outnumber girls under ten and since some families have more than one child under ten, it follows that at least one girl under ten has more than one brother under ten.
Wrong. This adds gender and family structure, but it does not follow from the same counting logic.
(D) At least one of the families in Herndon has more than one child, since in Herndon, there are fewer families than children and every child is a member of a family.
Correct. This exactly matches the structure: more children than families, and every child belongs to a family, so at least one family must have more than one child.
(E) There must be fewer families that include teenagers than there are teenagers belonging to such families, since there is at least one family that includes more than one teenager.
Wrong. This reverses the reasoning. The original uses “more items than containers” to prove that one container has multiple items; this choice uses one container with multiple items to infer a comparison.
Answer: (D)