Final answer:
A dual alternative decision structure in programming allows a program to execute one set of statements or another based on a condition being true or false, typically using an if-else statement.
Step-by-step explanation:
The dual alternative decision structure, also known as a binary decision or a two-way selection, is a control structure used in programming that allows a program to execute one set of statements or another based on whether a condition is true or false. It essentially asks a question, and depending on the answer (yes or no), it takes one of two possible actions.
For instance, if a program needs to choose between two courses of action based on a user's input, the if-else statement would be used. A simple example in pseudocode:
IF (condition) THEN
action1
ELSE
action2
END IF
If the condition evaluates to true, action1 will be executed. If the condition evaluates to false, action2 will be executed. This type of structure is fundamental in many programming languages and is an essential part of decision-making in programming.