**Core Concept**
Post spinal headache, also known as post-dural puncture headache (PDPH), is a complication that can occur after dural puncture during spinal anesthesia. It is caused by the leakage of cerebrospinal fluid (CSF) through the dural puncture site, leading to a decrease in CSF pressure and subsequent stretching of the meninges, which can cause pain.

**Why the Correct Answer is Right**
The headache typically develops within 24-48 hours after the procedure and can last for several days or even weeks. The duration of the headache can vary depending on the size of the dural puncture, the type of needle used, and the patient's overall health. In most cases, the headache will subside on its own within 7-10 days, but it can persist for up to 2 weeks in some individuals.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because PDPH can last longer than 1 week in many cases.
**Option B:** This option is incorrect because while caffeine and hydration can help alleviate symptoms, they do not affect the duration of the headache.
**Option C:** This option is incorrect because while some cases of PDPH may resolve within 3-5 days, this is not a universal experience and many patients will experience a longer duration of symptoms.

**Clinical Pearl / High-Yield Fact**
To reduce the risk of PDPH, it is essential to use a small-gauge needle and to minimize the number of punctures required for the procedure. Additionally, patients should be advised to maintain adequate hydration and to avoid heavy lifting or bending in the days following the procedure.

**Correct Answer: C. 7-10 days.**