Final answer:
The linear function among the given options is the one where a straight line starts from the y-axis and slants down in the first quadrant.
Step-by-step explanation:
Linear functions are mathematical relationships between variables that form straight lines when graphed. They have the form f(x) = mx + b, where "m" is the slope and "b" is the y-intercept. Linear functions exhibit constant rate of change and are fundamental in algebra and geometry.
The linear function among the options provided is the one where a straight line starts from the y-axis and slants down to a certain point in the first quadrant, then down again with a different slope, and then down again at another slope. All the line segments are straight lines in the first quadrant.