Choose the option that best complete the gap (s) Yours is to command.....is to obey

Analyze the question

The sentence is: "Yours is to command, __ is to obey." We need the word that correctly fills the gap. It must be a pronoun that can stand alone as the subject of "is to obey", and it should parallel "Yours".

Explain the concept

"Yours" is a possessive pronoun. Possessive pronouns stand alone without a noun after them, and they never take an apostrophe:

• mine
• yours
• his / hers
• ours
• theirs

Possessive adjectives like their must come before a noun (e.g. "their duty"). They cannot stand alone.

Solution

1. The gap is the subject of "is to obey", so it needs a pronoun standing alone: "___ is to obey".
2. Option C, "their", is a possessive adjective. It needs a noun after it, so it is wrong here.
3. Options A (theirs') and B (their's) both have apostrophes. Possessive pronouns never take apostrophes, so both are wrong. (Note that "their's" is not a word at all.)
4. Option D, "theirs", is the correct possessive pronoun. It matches "Yours" in structure:

"Yours is to command, theirs is to obey."

Tip

Apostrophes show contraction (it's = it is) or possession by nouns (the boy's book). They are never used in possessive pronouns: yours, hers, ours, theirs, its. If a pronoun stands alone and shows ownership, drop the apostrophe.