Final answer:
The statement about grouped frequency distributions having between 5 to 12 classes is true as a general guideline, allowing for effective data representation and ensuring that each data item is included in only one class.
Step-by-step explanation:
The statement, "A grouped frequency distribution should have from 5 to 12 classes," is generally considered true. The reason for this is based on a guideline rather than a strict rule. Grouped frequency distributions are used to simplify data and make it easier to understand. There should be enough classes to accurately represent the data but not so many that the table becomes overly complex. Most statisticians recommend between 5 and 20 classes, depending on the data set. The key is to ensure that the class intervals make sense for the distribution of data and that each data item belongs to only one class, which supports option C. Moreover, having multiple data items in each class leads to a better summary and visualization of the overall distribution of the data set.
Option D, which suggests there can be multiple classes for each data item, is false. In a grouped frequency distribution, each data item can only fall into one class interval. If a data item could belong to multiple classes, this would lead to a misleading representation of the data.