Which sentence best states the main idea of this passage

The twin towers were a New York city landmark at 110 stories each
The seven underground levels included stores and a subway station
They were completed in 1973
Everyday around 50,000 people went to work at companies with offices inside the towers

The twin towers were a New York City landmark at 110 stories each.

The main idea of this passage is that the twin towers were a significant New York City landmark.

To determine the main idea of a passage, you should look for the sentence that summarizes the central point or the overall message of the passage. In this case, it would likely be the sentence that encompasses the most important information. Let's examine the options:

1. "The twin towers were a New York city landmark at 110 stories each."
2. "The seven underground levels included stores and a subway station."
3. "They were completed in 1973."
4. "Everyday around 50,000 people went to work at companies with offices inside the towers."

The first option mentions the twin towers being a landmark, but it fails to capture the main idea of the passage. The second option focuses on the underground levels but doesn't encompass the key details of the passage. The third option provides the completion date but is not the main focus. The fourth option, however, highlights the fact that around 50,000 people worked at companies inside the towers daily. This detail serves as the main focal point of the passage and, therefore, best states the main idea.