Which of the following can cause a high SWR reading?

A high SWR reading means that a large portion of your transmitted signal is being reflected back to the radio rather than radiating out of the antenna. An open circuit (such as a broken wire) or a short circuit (where the center conductor touches the outer shield) represents an extreme impedance mismatch. This causes almost all power to be reflected, resulting in a very high SWR. Changing the length or type of standard 50-ohm coaxial cable, like swapping RG-213 for RG-58, does not inherently cause a high SWR because the characteristic impedance remains matched. Grounding the shield at the building entrance is a standard safety practice and has no negative effect on SWR.