Step 1: Read the sentence carefully to understand the relationship between the two ideas being connected. One idea refers to going to the shopping center, while the other states that the shops were closed. These two ideas clearly stand in contrast to each other.
Step 2: Analyze the function of each given connector:
- because — is used to introduce a reason or cause, not a contrasting idea, so it is incorrect here.
- or — is used to present a choice or alternative, which does not fit the intended meaning.
- but — is specifically used to show contrast between two opposing or unexpected ideas, making it appropriate in this context.
- so — expresses a result or consequence, which changes the intended meaning of the sentence.
Step 3: Since the sentence requires a connector that clearly expresses contrast, the most logical and grammatically correct choice is but.