Final answer:
The best response by the nurse would be to reassure the client that it is normal for the colostomy to appear larger initially.
Step-by-step explanation:
The best response by the nurse to the upset male client would be 'It's normal for it to appear larger initially.' It is important for the nurse to reassure the client and provide accurate information. By informing the client that it is normal for the colostomy to appear larger initially, the nurse can help alleviate the client's concerns and reduce anxiety.