To determine how many people in the sample have three or more pets in their household, we need to analyze the given responses. Based on the formatting of your question, it seems like there might be some missing information that would help us to identify how many respondents reported having three or more pets.
From the options provided ("3", "7", "18", "6"), it seems like you may need to select one of these numbers. However, without additional information on the sample data, I cannot determine the correct answer.
If you have survey data or a summary of how many pets each respondent has, please provide that information so I can help you find the answer.