The correct answer is D) half hitch. The half hitch is a simple knot that is indicated by the letter "U" in the illustration D030DG. The half hitch is a common knot used to temporarily secure the end of a line to another object or line. It is a fundamental knot that is often used in seamanship and is a required knot for the US Coast Guard Captain's License Examination. The other options are incorrect because: A) a round knot is a different knot, B) a becket bend is used to join two lines together, and C) a plain whipping is used to wrap the end of a line to prevent it from fraying, rather than to secure it to another object.