Which knot is commonly used to secure a rope to a fixed object?

The bowline knot is commonly used to secure a rope to a fixed object because it creates a fixed loop at the end of the rope that does not slip or jam under load. This knot is particularly valuable in rescue operations and other scenarios where a strong and secure connection is needed, allowing for easy untie after the load is removed.

In contrast, while the double overhand knot provides a secure binding, it does not form a loop that can be used to secure a rope to a fixed point. The sinternal knot is not a standard term generally recognized in knot-tying practices and is likely a misnomer, which makes it irrelevant as a suitable option. The half hitch, while useful for binding objects together or adding security to other knots, does not create a reliable fixed loop and is generally used in conjunction with other knots rather than as a standalone option for securing to fixed objects.

Overall, the bowline knot's characteristics make it the most effective choice for securing a rope to a fixed object due to its reliability and ease of untying after exertion of force.