What is 4 in the morning 3 at lunch and 2 in the evening?

The answer to the riddle "What is 4 in the morning, 3 at lunch, and 2 in the evening" is the letter "o." In the Word "morning," there are four letters; in "lunch," there are three letters; and in "evening," there are two letters. Thus, it highlights the number of letters in each respective Word at different times of the day.