Solve.

x-1=3
Select the correct choice below and, if necessary, fill in the answer box to complete your choice.
• A. The solution set is
3. (Use a comma to separate answers as needed.)
• B. The solution is the empty set.

To solve the equation x-1=3, we'll isolate the variable x by adding 1 to both sides:

x - 1 + 1 = 3 + 1
x = 4

Therefore, the solution set is {4}.

So the correct choice is A. The solution set is 4.