I don't think some will write the whole program here, but which part are you having trouble with?
Answer:
d. The trigger is fired more than once.
Explanation:
What would happen in this situation is that the trigger would be fired more than once. This is because the trigger will be fired when the user updates the record. It will also be fired when the process builder is run.
If the trigger fires more than once, this can be problematic for the developer. Therefore, it is better if the trigger fires just once, as this is the time when the present changes can be placed.
Answer:
Incremental technique is the way in which software is built and delivered in pieces. The concept is to keep the client and developer on same page and the client is known as a non tech person, so he should be given software in piece by piece to avoid any confusion and sudden change.
Agile method is the best example of this technique in which steps are defined on contract basis and the software is delivered and build by pieces to keep client and developer on same page.