Which choice completes the text so that it conforms to the conventions of Standard English?

Question

At the state robotics competition, each team builds a single machine to cross an obstacle course without recharging. Endurance often decides the event: last year the winning ____ battery kept it moving for nearly six hours.

Accepted Answer

B. robot's. The battery belongs to one machine — “the winning robot” — so the singular possessive “robot's” is required. (A) is the plain plural, showing no possession at all, the error of hearing an /s/ sound and adding a plural ending instead of an apostrophe. (C) is the plural possessive, which would wrongly indicate that several winning robots share one battery; the text specifies that each team builds “a single machine” and that there was one winner. (D) is a nonstandard form: a plural noun already ending in -s takes only an apostrophe, never an extra -'s.

Answer

A. robots — This plain plural shows no possession at all; the battery belongs to the winning robot, so you need an apostrophe, not a plural ending.

Answer

C. robots' — The plural possessive would mean several winning robots shared one battery, but the text says each team builds "a single machine" and there was one winner.

Answer

D. robots's — A plural ending in -s takes only an apostrophe, never an extra -'s — and here the owner is singular anyway.

Standard English Conventions practice question

Answer: B. robot's

Why the other answers are wrong

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