The underscored statement is true, and the reason for it or result of it is
The underscored statement is true, but the reason or result is false.
The underscored statement is false.
A track with low traffic density requires extra maintenance because the lack of
compacting weight from the trains allows ballast to spread.
In the United States, steepness of a grade is given in percent, arrived at by
dividing the length of a grade by its radius.
The 56 1/2-inch gage is used on railroads in the United States because
derailment is more frequent where smaller gages are used.