A city's public transportation system uses two types of buses: standard buses and articulated buses. A standard bus can carry 40 passengers, and an articulated bus can carry 60 passengers. On a particular day, the buses transported a total of 2,500 passengers. The equation represents this situation, where is the number of standard buses used and is the number of articulated buses used. Which of the following is the best interpretation of the term in this context?
The total number of passengers transported by standard buses
The total number of articulated buses used
The total number of passengers transported by articulated buses
The number of passengers an articulated bus can carry
