Which artery's linear guide runs from the center of the antecubital fossa to a point between the 4th and 5th fingers?

The ulnar artery is the correct choice because its linear guide follows a pathway that begins at the center of the antecubital fossa, a triangular area at the front of the elbow. From this point, the ulnar artery travels down the forearm towards the wrist. Specifically, it moves toward a location between the fourth and fifth fingers, which corresponds to its terminal branches that contribute to the hand's vascular supply.

The other options do not align with this path. The brachial artery primarily runs down the upper arm and bifurcates into the radial and ulnar arteries at the elbow, making it irrelevant for this specific linear guide. The radial artery, while also a branch of the brachial artery, runs toward the thumb side of the forearm and wrist, not towards the fourth and fifth fingers. Lastly, the femoral artery is located in the thigh and is not connected to the forearm or hand structure at all, making it unrelated to this context.