这题不是说让题目中的两个变量放在一个图里吗

问题如下：

A line chart with two variables-for example, revenues and earnings per share-is best suited for visualizing:

选项：

A.the joint variation in the variables. B.underlying trends in the variables over time. C.the degree of correlation between the variables.

解释：

B is correct. An important benefit of a line chart is that it facilitates showing changes in the data and underlying trends in a clear and concise way. Often a line chart is used to display the changes in data series over time. A is incorrect because a scatter plot, not a line chart, is used to visualize the joint variation in two numerical variables. C is incorrect because a heat map, not a line chart, is used to visualize the values of joint frequencies among categorical variables.