Final answer:
A curvilinear relationship is the proper term for a relationship between two variables where the strength and/or direction changes over their range, resulting in a curved line when graphed. Option C
Step-by-step explanation:
The correct word to fill in the blank is curvilinear. A curvilinear relationship is one between two variables whereby the strength and/or direction of their relationship changes over the range of both variables. Unlike a linear relationship, which produces a straight line when graphed and can be expressed by the equation y = mx + b, a curvilinear relationship results in a curved line.
This means that as the independent variable changes, the rate of change of the dependent variable is not constant but varies, typically in a nonlinear manner.
Examples of various types of relationships include linear, quadratic, inverse, and exponential, each with distinct graphical representations.
In the case of a directly proportional relationship, which is a special case of a linear relationship, as one value increases, the other value increases at a consistent rate, represented by the equation y = kx. The correlation coefficient, usually denoted as r, is used to measure the strength and direction of a linear relationship between two variables. Option C