The correct answer is A) disconnecting coil ends, insulating each, and short circuiting the two commutator bars. This is the correct answer because it describes a temporary repair method that can be used to allow continued operation of an open DC propulsion armature coil until permanent repairs can be made. By disconnecting the coil ends, insulating them, and shorting the commutator bars, the open circuit in the coil is isolated, preventing further damage and allowing the motor to continue running, albeit with reduced power output. The other options are incorrect because B) connecting the coil ends directly to brushes would create a short circuit, C) grounding the coil ends would not resolve the open circuit, and D) removing the sparking brushes would not address the open coil issue.