The duration of effect of a regional anesthetic depends on

After surgery, numbness and weakness persist for a period of time that depends on the location of the injection and the type of anesthetic medication. Some forms of regional anesthesia can last up to 24 hours. Spinal anesthesia may cause difficulty urinating in the first several hours after surgery until bladder sensation returns.

Explanation:

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C. too many exceptions to each concept

Explanation:

The exemplat model is a model created to learn, and how people develop thei understanding of society and life, the main problem with it is that once you start actually developing it has too many exemptions in each concept that it turns impossible to remember all of them.