Final answer:
Carlos should use a RAD tool or prototyping software to quickly sketch his application idea instead of coding languages. A computer systems engineer hires a painter as it's more efficient and aligns with his professional skill set.
Step-by-step explanation:
Carlos is looking for a rapid application development (RAD) solution to sketch out his application idea without writing actual code. In this scenario, none of the listed programming languages (Python, Java, HTML/CSS, JavaScript) are directly suited for RAD prototyping. Instead, Carlos should use a RAD tool or a prototyping tool like a mockup or wireframe software that allows him to create a visual representation of the application's user interface and functionality without coding. These tools are designed specifically for quick and efficient preliminary designs to illustrate concepts and gather feedback.
To answer the unrelated question from the provided information, a computer systems engineer may opt to hire a painter to paint his house because he might not be as skilled in painting, making it more practical and efficient to utilize a professional painter's services. This allows the engineer to focus on his area of expertise and use his time more valuably.