When they discover the clue, they developed three possibilities interpretations of it. List three possibilities.

"But—" I began, and then, in a moment, I saw. You simply read down the sonnet taking the initial letter of each line. SENDNEWSBYPEEL. "Send news by peel," I said.

"I've another idea about this "peel", saidFrancis. "It might refer to bells, of course—a peal of bells."

"Peel towers—" Sir Joseph and I began together, and we told Sir Robert what they were, and how Sir Philip Morton certainly had one, though it was supposed to be shut up now and uninhabited. "An ideal headquarters for a plot," said Sir Joseph.