What component is used to hold leads vertically for driving bearing piles?

The correct answer is the catwalk, which serves an important function in the context of driving bearing piles. A catwalk is designed to provide stability and support for the leads, which are the guiding structures used during the driving process of piling. By holding the leads vertically, the catwalk ensures the accurate alignment of the pile as it is driven into the ground. This alignment is crucial for maintaining the integrity of the installation and ensuring that the piles are driven to the correct depth and at the required angle.

In contrast, while a winch is typically used to lift and lower loads and may assist in some operation aspects, it does not provide vertical support for leads like a catwalk does. A boom is generally more related to the lifting or placement of heavy objects and may not specifically hold the leads in place. A stabilizer assists in reducing movement and maintaining equilibrium but does not directly support the vertical positioning of leads during pile driving. Thus, the catwalk is specifically designed for this purpose, making it the most suitable choice for holding leads vertically.