4. Henry and Rick / a dog

Short Explanation

To form questions with 'have/has got', we place 'have' or 'has' at the beginning, followed by the subject and then 'got a...' or 'got an...'. Short answers are 'Yes, I/you/we/they have' or 'No, I/you/we/they haven't' for 'have', and 'Yes, he/she/it has' or 'No, he/she/it hasn't' for 'has'.

Step-by-step solution

1. Step 1: Form the question. Since 'Henry and Rick' is a plural subject, we use 'Have'. The question is 'Have Henry and Rick got a dog?'.
2. Step 2: Provide a short answer. Assuming Henry and Rick have a dog, the answer is 'Yes, they have'.

Answer: Have Henry and Rick got a dog? Yes, they have.