Choose the correct form of following words, out of four given options as in…

Short answer: Both "He lost his all in speculation" and "All spoke in her favour" use "all" as a pronoun functioning as a noun. If only one option can be chosen, "He lost his all in speculation" is the clearest example of "all" meaning "everything he owned" (a noun referring to possessions).

Detailed explanation for each sentence:

• He lost his all in speculation — "all" is a pronoun used as a noun meaning "all his possessions" or "his entire fortune." It is modified by the possessive "his" and serves as a noun phrase.

• All men are mortal — "all" is a determiner/quantifier modifying the noun "men" (meaning "every"); it is not functioning as a noun here.

• He was all alone when I saw him — "all" is an adverbial intensifier modifying the adjective "alone" (meaning "completely alone"); it is not a noun.

• All spoke in her favour — "all" is a pronoun meaning "everyone" and functions as the subject, so it also serves a noun-like role.

Recommendation:

• Clarify the scoring rule: if any pronoun use that functions as a noun is acceptable, accept both sentences that use "all" as a pronoun (the possessions example and the "everyone" subject example).

• If only the noun meaning 'all possessions' is intended, mark "He lost his all in speculation" as the single correct answer and update the question to specify that meaning.