Topic: Conjunction,

Best Answer Explained in Below-:

The correct choice to join the sentences "She was waiting for a taxi. She found a car broken down." is A) "when." This conjunction serves to indicate a specific moment in time when one event occurs in relation to another. In this case, when she was waiting for a taxi, she simultaneously discovered a car that was broken down.

Using "when" effectively conveys that these two actions are linked in a temporal sequence; her waiting for the taxi coincides with her finding the broken-down car. It suggests that the discovery of the car was an unexpected occurrence during her wait, creating a narrative flow.

In contrast, the other options do not fit the context as well. "And" would imply a simple addition of information rather than a specific timing relationship. "Yet" introduces a contrast, which does not apply here because there’s no conflicting idea. "As if" suggests a hypothetical situation, which does not accurately reflect the factual nature of the events. Therefore, "when" is the most suitable word to connect these two thoughts meaningfully.