The data set consists of four pairs, where the first element represents a number and the second element represents a letter. The pairs are: 1, A, 2, A, 3, B, and 4, B. This indicates that the numbers 1 and 2 are associated with the letter A, while the numbers 3 and 4 are linked to the letter B. In summary, there are two distinct groups based on the letters. The letter A corresponds to the numbers 1 and 2, while the letter B corresponds to the numbers 3 and 4. This categorization shows a clear division between the two letters based on their associated numbers.