Before attaching the towline, make certain the fitting attachment it is to be attached to is ________________________________ to the deck with through bolts and backing plates.

The correct answer highlights the importance of safety and security when preparing to attach a towline. Ensuring that the fitting attachment is secured to the deck with through bolts and backing plates is crucial because it guarantees the structural integrity of the towing setup. A secured fitting can withstand the stresses involved in towing, such as sudden jerks or heavy loads, ensuring that the towline remains intact and preventing potential accidents or equipment failure.

The focus on securing fittings emphasizes that they must be properly installed and bolstered to avoid any risk during towing scenarios. This consideration is vital for the safety of both the boat crew and the vessel being towed. Properly secured fittings also promote operational reliability, which is essential in any mission.

While the other options may have their contexts, they do not adequately capture this critical safety aspect. Visibility relates to being able to see the fitting, wild does not pertain to its installation, and expensive does not contribute to the safety or functionality of the attachment when towing. Therefore, prioritizing a secured fitting is essential for safe operations in towing situations.