Which of the following best describes the meaning of the word "underpinned"?

Concept: A "word-meaning" (synonym) question asks for the option whose meaning most closely matches the target word in normal usage. The verb "underpin / underpinned" means to support, justify, or form the underlying basis or foundation for something.

Application: Because "underpinned" centres on providing support or a foundation, the closest single-word match is "supported". Test it by substitution: "Her evidence underpinned the conclusion" = "Her evidence supported the conclusion" — the sentence keeps the same meaning, confirming the match.

Contrast with the other choices:

• Bolstered means strengthened or reinforced. It is a near-synonym, but it emphasises increasing existing strength rather than forming the underlying basis, so it is not the closest match for "underpinned".

• Advocated means publicly recommended or argued in favour of something — an act of persuasion, not of providing support or a foundation.

• Prepared means made ready in advance. It conveys readiness, not foundational support, so it does not fit the meaning of "underpinned".