The correct answer is B) form a temporary eye (loop) at the end of a line. The bowline is a common knot used to form a loop or eye at the end of a line. This loop can be used to attach the line to an object, such as a cleat or a ring. The bowline is a reliable and secure knot that will not slip or bind, making it a popular choice for a variety of boating and sailing applications. The other answer choices are incorrect because: A) the bowline is not used to join lines of equal size, C) the bowline does not prevent a line from fraying, and D) the bowline is not a stopper knot.