Who used the alias Vincent Spaulding? a. Sherlock Holmes b. Dr. Watson c. Mr. Merryweather d. John Clay

The answer to your multiple choice question is d. John Clay. Sherlock Holmes first hears this name when he asks his prospective client Jabez Wilson:

“What is the name of this obliging youth?”

Wilson's reply makes Holmes, who is already suspicious, become even more suspicious of the assistant.

“His name is Vincent Spaulding, and he's not such a youth, either. It's hard to say his age. I should not wish a smarter assistant, Mr. Holmes; and I know very well that he could better himself and earn twice what I am able to give him. But, after all, if he is satisfied, why should I put ideas in his head?”

The idea of Wilson putting ideas into Spaulding's head is unintentionally ironic, since Spaulding has put such fantastic ideas into Wilson's head. Before the interview with Wilson is over, Sherlock Holmes is already positive that the man who is calling himself Vincent Spaulding must be none other than the elusive criminal whose real name is John Clay. Later in the story Peter Jones, the man from Scotland Yard, will describe him to the bank director as follows:

“John Clay, the murderer, thief, smasher, and forger. He's a young man, Mr. Merryweather, but he is at the head of his profession, and I would rather have my bracelets on him than on any criminal in London. He's a remarkable man, is young John Clay. His grandfather was a royal duke, and he himself has been to Eton and Oxford. His brain is as cunning as his fingers, and though we meet signs of him at every turn, we never know where to find the man himself.

John Clay is wanted for many crimes, including murder, but neither Sherlock Holmes nor Scotland Yard has been able to catch up with him. Holmes is more than willing to take Wilson's case on a pro bono basis because this seems like a golden opportunity, not only to catch John Clay, but to catch him red-handed in a crime for which he will certainly be hanged. 

Jabez Wilson is fortunate that he never had enough curiosity to go down into his own cellar to see what Vincent Spaulding was up to down there. The author, Arthur Conan Doyle, portrays Wilson as old, overweight, and apparently suffering from high blood pressure. This would explain why Wilson never went down those dark wooden steps, which would be much harder to climb back up. He is also addicted to snuff, which is a powdered tobacco and which could affect his breathing in the same way as tobacco smoked in a pipe, cigar or cigarette. If Wilson had caught this "Vincent Spaulding" digging a tunnel, John Clay would have had no qualms about murdering him with his shovel and burying him in his own cellar.

Because of the ingenious way in which this story is told, the reader does not actually meet the notorious and dangerous John Clay until he pops out of his tunnel through the flooring and into the bank's strongroom. He proves to be a very cool customer, even though he has been trapped and faces hanging in those strict Victorian times. His attempted burglary alone would be enough to get him hanged, but he has a long list of prior crimes for which to answer.