input: Write a function to classify data based on the first element of the list.
  assert classify_data([4, 5, 8, 1, 9]) == 'Category A'
  assert classify_data([6, 3, 2, 7]) == 'Category B'
  assert classify_data([5, 1, 0, 4, 3]) == 'Category A'
  assert classify_data([10, 1, 1, 1]) == 'Category B'
output: def classify_data(data):
      if data[0] < 6:
          return 'Category A'
      else:
          return 'Category B'