Which of the following is a complete sentence?

To determine which of the following is a complete sentence, we need to understand what a complete sentence is. A complete sentence must have a subject (which tells us who or what the sentence is about) and a predicate (which tells us what the subject is doing or what is being done to the subject).

Let's examine the choices provided and see if they meet these criteria:

1. "Running down the street."
This is not a complete sentence because it is missing a subject. It seems like a participial phrase, which is used to provide additional information but cannot stand alone as a complete sentence.

2. "Although he tried."
Similar to the previous choice, this is not a complete sentence because it is missing a subject. It also seems to be a subordinate clause used to introduce a dependent idea.

3. "She ate a delicious apple."
This is a complete sentence. It has a subject ("she") and a predicate ("ate a delicious apple") that tells us what the subject is doing.

4. "Beautiful flowers in the garden."
This is not a complete sentence because, like the first choice, it lacks a subject. It appears to be a noun phrase describing something but cannot function as a complete sentence on its own.

Based on our analysis, the correct answer is choice number 3: "She ate a delicious apple."