There are 9 seventh grade classes and 9 sixth grade classes at central middle school. one of these classes will be randomly selected to participate in a survey. which statement explains how to find the probability that mr. ramirez's seventh grade class will be selected? why?

a. the denominator is the number of seventh grade classes. the numerator is represented by mr. ramirez's class because it is the only seventh grade class being considered.
b. the denominator is the total number of classes. the numerator is the number of seventh grade classes because all of the seventh grade classes are being considered.
c. the denominator is the total number of classes. the numerator is represented by mr. ramirez's class because it is the only seventh grade class being considered.
d. the denominator is the number of seventh grade classes. the numerator is the number of sixth grade classes because it is less likely that a sixth grade class will be picked.