Which of the following actions by F1 is considered legal while on the pitcher's plate?

When considering the actions of a pitcher on the pitcher's plate, it's important to recognize the rules governing pitcher behavior and how they interact with the game. Each action listed can indeed be interpreted as legal within the context of the rules.

Bringing hands together without starting the delivery is permissible because this is often part of a pitcher's routine as they prepare to throw, and it does not violate any aspects of the pitching rules.

Adjusting the cap is also legal. Pitchers often need to ensure their equipment is secure and comfortable. It's a common practice to make these adjustments to maintain focus and control while preparing to pitch.

Shaking off a pitch signal with the head is another legal action. This is a way for pitchers to communicate with catchers without calling timeout or creating a distraction, allowing for fluid gameplay.

When these actions are viewed collectively, they all adhere to the established rules and practices for pitchers in the game, indicating that they can perform these actions while legally on the pitcher's plate. Therefore, the answer encompasses the legality of all these actions, affirming that each is within the permissible conduct for pitchers in a game situation.