Answer :

To determine the number of US troops in Vietnam by 1969, we can analyze the historical data available. During the Vietnam War, the United States significantly increased its military presence over time. By the year 1969, the peak of US troop involvement had been reached.

Given the options provided:

- 50,000
- 100,000
- 500,000
- 1,000,000

We need to select the most accurate figure representing the number of troops. After careful consideration of the data:

In 1969, approximately 500,000 US troops were stationed in Vietnam.