Final answer:
To find the equation of the specified line, one must identify the slope, which is the coefficient of x in the equation y = mx. However, none of the provided equation options match a slope of 3, as discussed related to FIGURE A1 in the supporting documents, suggesting a discrepancy in the question.
Step-by-step explanation:
To determine which of the given options A through D is the equation of the specified line, we need to figure out the slope of the line. The slope is represented by the coefficient of x in the equation y = mx, where m is the slope. If we refer to FIGURE A1 mentioned in the reference materials which discusses the algebra of straight lines, it states that for a given rise of 3 on the y-axis for every 1 unit increase on the x-axis, the slope (m) of the line would be 3. Therefore, none of the options provided (A. y = 6x, B. y = 1/2x, C. y = 1/6x, D. y = 2x) match a line with a slope of 3, indicating there could be an error in the question or more information may be needed to accurately address the student's query.