Each question below has blanks, each blank indicating that something has been…

Concept: An indefinite article (a/an) marks a noun's first, non-specific mention, and the choice between a and an depends on the sound that follows — a before a consonant sound, an before a vowel sound. The definite article (the) marks a noun that is already specific: either it was named earlier in the same discourse, or it names something so well known and complete that everyone understands exactly which thing is meant (a fixed idiomatic set, for instance).

Application:

1. First blank — "___ hot tear rolled into her lap": the tear is being named here for the very first time, and the word right after the blank, "hot", opens with a consonant sound, so this blank takes the indefinite article suited to a consonant sound.

2. Second blank — "formed itself into ___ pearl": the pearl, too, is being introduced for the first time — nothing earlier in the passage refers to it — so it again takes the indefinite article suited to a consonant-sounding word.

3. Third blank — "glowing with all ___ colours of the rainbow": this is the fixed, familiar phrase for the rainbow's one complete, universally recognised set of colours, so the blank takes the definite article — never an indefinite one, since the set itself is not being newly introduced.

4. Fourth blank — "___ angel seized it": this two-sentence extract continues a longer story in which a guardian angel has already appeared earlier in the narrative. By this point the sentence is pointing back to that same, already-established angel rather than introducing a new character, so this blank also takes the definite article.

Cross-check:

• One listed set gives the pearl a definite article on its first mention and gives the fixed rainbow-colours phrase an indefinite article — both go against how a first mention and a complete, well-known set are normally marked.

• Another listed set opens by giving the tear a definite article, as if a tear had already been named earlier in the passage, when nothing before this sentence introduces one.

• "None of the above" would only hold if no listed set could satisfy every blank together — but once the fourth blank is read as pointing back to an angel already present in the surrounding story rather than a brand-new one, one of the listed sets does satisfy all four blanks.

Working through the four blanks together, the set that fits every one of them is: a, a, the, the.