Step 1: Understanding the Concept:
This problem requires the application of correct English grammar rules, specifically focusing on Subject-Verb Agreement and identifying the appropriate Verb Tense based on contextual time markers.
Step 2: Key Formula or Approach:
1. Identify the Subject: Determine whether the subject is singular or plural. Collective nouns require specific rules.
2. Identify the Tense Indicator: Look for timeline markers like "since" or "for" to choose the correct aspect of the verb.
3. Select the Auxiliary Verb: Combine the singular/plural rule with the tense rule to find the precise fit.
Step 3: Detailed Explanation:
- Subject Analysis: The subject is "The fusion band". A "band" is a collective noun. In standard English grammar, a collective noun is treated as a singular unit when the group acts together as a single entity. Therefore, it requires a singular verb form.
- Tense Analysis: The phrase contains the keyword "since 9 a.m.". The word "since" indicates an action that started at a specific point in the past (9 a.m.) and is still continuing into the present moment. This requires the Present Perfect Continuous Tense structure:
\[ \text{Subject} + \text{has/have been} + \text{Verb(-ing)} \]
- Elimination process:
- "were" (Option C) and "are" (Option D) are plural past and present continuous verbs and do not match the time clue "since".
- "have been" (Option A) is the present perfect continuous form, but it is plural.
- "has been" (Option B) is the singular present perfect continuous form, which matches our singular collective noun perfectly.
Step 4: Final Answer:
The complete grammatically correct sentence is: "The fusion band has been playing since 9 a.m."