Final answer:
The lumbar and sacral plexuses receive contributions from L4, with the former supplying nerves to the pelvic region and anterior leg, and the latter giving rise to the sciatic nerve which extends across the hip joint.
Step-by-step explanation:
The question asks, Which two nerve plexuses receive contributions from L4? The correct answer is C) Lumbar and Sacral plexuses. The lumbar plexus arises from all the lumbar spinal nerves and gives rise to nerves enervating the pelvic region and the anterior leg. Among the major nerves from this plexus is the femoral nerve. Similarly, the sacral plexus originates from the lower lumbar nerves L4 and L5 as well as the sacral nerves S1 to S4, giving rise to the sciatic nerve which is a major systemic nerve extending across the hip joint.