The correct answer is: D. Nested selection structure
A nested selection structure is a selection structure that is contained within another selection structure. The inner selection structure is executed only if the condition in the outer selection structure is true.
Option A is incorrect because an implicit selection structure is a selection structure that is not explicitly stated in the code. It is created by the compiler when a variable is declared with the Option Explicit statement.
Option B is incorrect because an inner selection structure is a selection structure that is contained within another selection structure. The inner selection structure is executed only if the condition in the outer selection structure is true.
Option C is incorrect because an outer selection structure is a selection structure that contains another selection structure. The outer selection structure is executed first, and then the inner selection structure is executed only if the condition in the outer selection structure is true.