Answer:
D. testing
Step-by-step explanation:
The testing stage is that stage where the developed application is put in the hands of potential users so as to gauge their experience with the product. Usually, a prototype that has the basic features of the main or original product is given to the potential user of an app. He is allowed to use the application for some time and is then later interviewed by the programmer to know what his experience was like when using it.
Through this means, any faults detected can be corrected by the programmer. This would also make the finished app better suited for the target users.