Step 1: Vernal keratoconjunctivitis is a seasonal allergic eye disease, classically affecting boys, with itching, ropy discharge and photophobia. It presents in palpebral, limbal and mixed forms, and each form contributes its own signs.
Step 2: In the palpebral form the upper tarsal conjunctiva develops hard, flat cobblestone papillae, which is the papillary hypertrophy mentioned in option c. This is one of the most recognizable signs of the condition.
Step 3: The limbal form produces Horner-Trantas spots, chalky white limbal accumulations of degenerating eosinophils, matching option b. Corneal involvement gives a shield ulcer, the shallow sterile epithelial ulcer high on the cornea in option a.
Step 4: Since the shield ulcer, the Horner-Trantas spots and the papillary hypertrophy are all genuine features of vernal disease, no single option can be excluded. The complete answer is therefore all of the above.
\[\boxed{\text{All of the above}}\]