RAD model , Waterfall model, incremental model, Agile model, prototype model or Spiral Model

Consider the following two scenario: A. ABC Software Company decides to build an Antivirus software. ABC is a large company and involves different kind of programmers: front end, backend, and full stack. The nature of viruses keeps change during the development process and ABC must respond to this change. The users will try the antivirus software, and their feedback will be considered to enhance the final version of the product. What is the best process model that ABC company can apply to develop the antivirus software? Explain your answer. [2.5 marks] B. A bank decides to build a new ATM software. All the Requirements are well-gathered and well-understood. There is no restriction on time, and the software can be released next year. The IT team at the bank are able to develop the required ATM software, and the client's feedback can be ignored at certain cases. What is the best process model that Bank can apply to develop the ATM sofiware? Explain your answer. [2.5 marks]