Final answer:
The posterior cutaneous nerve of the thigh receives contributions from the ventral rami of S1 to S3, which are part of the sacral plexus.
Step-by-step explanation:
The posterior cutaneous nerve of the thigh is a sensory nerve that arises from the sacral plexus. The sacral plexus itself is formed by the contributions from the lower lumbar and sacral spinal nerves. Specifically, the posterior cutaneous nerve of the thigh receives contributions from the ventral rami of S1 to S3. Therefore, the correct answer to the question is A) S1-S3.