A Ruby developer is searching for a lightweight web application framework that supports third-party library extensions. What should they choose?

Choosing Ramaze is fitting for a Ruby developer seeking a lightweight web application framework that supports third-party library extensions. Ramaze is specifically designed for Ruby, emphasizing simplicity and speed. It allows developers to construct applications with minimal overhead while providing features for incorporating additional libraries seamlessly. This flexibility makes it ideal for developers looking to create custom applications efficiently.

In contrast, the other frameworks listed cater to different programming languages or have different focuses. Apache Struts is a Java framework known for building enterprise-level applications but lacks the lightweight nature that Ramaze offers. Django is a prominent web framework for Python, known for its robustness and built-in functionalities, but it does not align with Ruby development. Twisted is an event-driven networking engine for Python, which, while powerful for asynchronous network applications, is not tailored for web application development in Ruby. Hence, Ramaze is the most suitable choice for the developer's specified needs.