The correct answer is: [C]: "Aquellos" .
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Note: We are referring to masculine plural ("los hijos") ;
We use "Aquellos" (not "Esos") ; since we are referring to "those (ones) over there."
"Aquellos" refers to masculine plural — (or mixed group of feminine and masculine—or even one masculine and any number of feminine) — and is an adjective modifying masculine nouns or group of masculine nouns, or a [group of masculine and feminine nouns—of which at least one noun is masculine]— for "those (ones) over there."
As such: "Answer choice: [C]: "Aquellos" ; is the correct answer.
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Note:
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Choice [A]: "Aquellas" ; refers to feminine plural — and an adjective modifying a feminine noun or group of plural feminine nouns— for "those (ones) over there."
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Choice [B]: "Aquello" ; refers to "that which" ; and does not modify a particular object, place, or person. "Aquello"—is neither masculine nor feminine. It is "neutral".
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Choice [D]: "Aquel" ; refers to masculine singular— and an adjective modifying a singular masculine Spanish noun — for "that (one) over there."
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→ Answer choice: [C]: "Aquellos" ; is the correct answer.
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