Final answer:
'Jgnnq' was deciphered by reversing Kate's method of shifting letters forward by two; when shifted back by two, it spells 'Hello'. Therefore, 'Jgnnq' was written by Kate.
Step-by-step explanation:
The word 'Jgnnq' could have been written either by Kate, who shifts each letter forward by two, or Bella, who uses the reverse of each letter’s position in the alphabet. To decipher, we can reverse the operations to see which one yields a meaningful word.
For Kate’s method, we shift each letter back by two: J becomes H, G becomes E, N becomes L, N becomes L, Q becomes O. So 'Jgnnq' shifted back by two is 'Hello'.
For Bella’s method, we reverse the position in the alphabet: J (10th letter) becomes Q (17th letter from the end), G (7th letter) becomes T (20th letter from the end), N (14th letter) becomes M (13th letter from the end), and so on. Applying this to all letters does not yield a recognizable word.
Therefore, 'Jgnnq' was written by Kate who shifts each letter forward by two.