A straight stream is briefly discharged through a window from the building exterior. This is typical of which type of attack?

The correct answer is the transitional attack. In firefighting, a transitional attack is characterized by the initial application of water through an exterior opening, such as a window, to cool the fire and reduce heat conditions before entering the structure. This method is particularly effective in situations where a quick application of water can lower the temperature and improve conditions inside, allowing for safer entry and more effective fire suppression.

A straight stream is often used in transitional attacks because it delivers a concentrated and powerful flow of water to penetrate the fire's immediate environment, which can help to control the spread of the fire. This technique is commonly employed when there is a risk of flashover or when heavy smoke and heat hamper visibility and access to the interior.

Other types of attacks, like combination and blitz attacks, involve different strategies and deployment methods that do not primarily focus on the initial exterior application of water through a window. The defensive attack generally aims to protect exposures and prevent the fire from spreading, and it does not typically involve entering the building or using straight streams in this manner. Therefore, understanding the context and techniques of a transitional attack elucidates why it is the most fitting answer in this scenario.