Final answer:
The student's question is true; rating is the percentage of households watching a specific show out of all households watching TV at a given moment.
Step-by-step explanation:
The question is regarding the concept of rating in the context of television viewership. A rating signifies the percentage of households that are watching a particular television program out of all households that have the TV on at that specific time. In the statement, it is proposed that the rating is a measure relative to all households watching television, which is true. In a broader context, studies and surveys are often conducted to analyze television viewing habits, such as the number of TV shows watched by children per day, or the mean number of hours spent watching TV by different demographics. This information can be used to form conclusions about viewing preferences and patterns in various regions or among different groups of people.