**Explanation:**

The correct answer is option 'c' - Both. The dog thought to serve himself to the strongest creature because he was afraid of other animals and was tired of looking for food every day. Let us discuss both reasons in detail:

**1. Afraid of other animals:**
The dog was afraid of other animals, which might have posed a threat to him. In the story, the dog states, "I am tired of running about and want to rest. I would rather be eaten by the strongest creature than live in constant fear of being attacked by others." This shows that the dog was living in fear and wanted to find a solution to escape that fear. By serving himself to the strongest creature, he hoped to find protection and security.

**2. Tired of looking for food every day:**
The dog was also tired of the constant struggle to find food every day. In the story, the dog mentions, "I have to run about all day long in search of food, and often I have to go hungry." This indicates that the dog was facing difficulties in finding enough food to sustain himself. By offering himself to the strongest creature, the dog thought that he would no longer have to worry about finding food and could finally have a sense of stability and contentment.

**Conclusion:**
In conclusion, the dog's decision to serve himself to the strongest creature was driven by both fear of other animals and exhaustion from the daily struggle to find food. The dog believed that by sacrificing himself, he could find protection from potential threats and escape the constant search for food.