In which position are the forearm bones opposite to each other at the wrist?

When the forearm bones, the radius and ulna, are in a position opposite to each other at the wrist, the body is in the prone position. In this position, the palm of the hand faces downwards, causing the radius—located on the thumb side of the forearm—to cross over the ulna, which is positioned on the pinky side. This crossing creates a situation where the two bones are not parallel, illustrating the opposite positioning described in the question.

In contrast, when in the supinated position, the palms face upwards, and the radius and ulna lie parallel to one another, making this position incorrect for the question asked. The extended and flexed positions refer to the angle of the elbow joint rather than the orientation of the forearm bones, which also would not apply to the scenario.