Choose the correct plural word from the list below.

English forms noun plurals through several distinct patterns:

• the regular "-s"/"-es" suffix;

• an irregular internal change that produces a plural form that is already complete (child -> children, woman -> women);

• an invariant noun that keeps the same form in the singular and the plural (sheep, deer);

• a hyphenated compound noun, where the plural marker attaches to the head noun rather than to the modifier that follows it (mother-in-law -> mothers-in-law, passer-by -> passers-by).

In "mother-in-law," the head noun is "mother" and "in-law" is a fixed modifier, so the plural marker attaches to the head noun, producing "mothers-in-law" while "in-law" stays unchanged.

Each remaining option applies a plural marker to a word that does not take one in that way:

• "childrens" adds "-s" onto "children," a form that already functions as the irregular plural of "child" and does not take a further plural suffix.

• "womans" attaches "-s" onto the singular "woman" without the internal vowel change that forms its actual plural, "women."

• "sheeps" attaches "-s" onto "sheep," a noun that keeps an identical form in both the singular and the plural.

Checking each form against a standard English dictionary confirms "mothers-in-law" as the recognized plural of "mother-in-law," while "childrens," "womans," and "sheeps" do not appear as valid entries.