Step 1: Understanding the Concept:
Articles ('a', 'an', 'the') are used to specify nouns.
The definite article "the" refers to a specific, previously mentioned item. The indefinite articles "a" and "an" refer to a general or non-specific item.
The rule for choosing between "a" and "an" is based entirely on the initial sound of the following word, not the letter it starts with.
Step 2: Detailed Explanation:
Let's analyze the noun in our sentence: "umbrella."
1. Specificity: The sentence "She bought... umbrella" suggests she bought any general umbrella from the market, not a specific one that we already know about. Therefore, we need an indefinite article.
2. Phonetic Rule:
- Use "a" if the word begins with a consonant sound (e.g., a ball, a cat, a university).
- Use "an" if the word begins with a vowel sound (e.g., an apple, an elephant, an umbrella).
3. Analyzing the Sound: The word "umbrella" starts with the letter 'u'. However, we must listen to the sound it makes.
The sound is /\textipa{2}/ (as in "uh-mbrella"). Since "uh" is a vowel sound, the rule dictates that we must use the article "an".
Contrast this with a word like "University." Although it starts with 'u', it sounds like "Yoo-niversity," which starts with a consonant /j/ sound. Thus, we say "a university" but "an umbrella."
Since "umbrella" begins with a distinct vowel sound, "an" is the only grammatically correct choice.
Step 3: Final Answer:
The correct article to fill the blank is option (B).