**Core Concept**
The question involves a case of surgical extraction of an impacted mandibular canine, which is a common oral surgical procedure. The use of a micromotor suggests a more complex procedure possibly involving sectioning of the tooth or removal of bone to access the impacted tooth. Post-operative pain and ecchymosis are potential complications.

**Why the Correct Answer is Right**
Although the specific correct answer choice is not provided, a likely cause for severe pain and ecchymosis following such a procedure could be related to trauma to the surrounding tissues, including nerves and blood vessels. The inferior alveolar nerve, which runs through the mandible, could be at risk during the extraction of a mandibular tooth, especially if the procedure was complicated.

**Why Each Wrong Option is Incorrect**
**Option A:** Without knowing the specifics, it's hard to comment, but generally, options that do not involve direct trauma or complication from the surgical site itself are less likely to be correct.
**Option B:** Similarly, without the text, we can speculate that options not directly related to surgical complications or anatomical structures involved in the procedure are incorrect.
**Option C:** This might be related to infection, which, while possible, typically develops over a longer period than immediately post-op.
**Option D:** Could be related to various factors, but without specifics, it's hard to assess its relevance.

**Clinical Pearl / High-Yield Fact**
It's crucial to recognize that the management of impacted teeth, especially in the mandible, requires careful planning and execution to avoid damage to vital structures like the inferior alveolar nerve. Post-operative pain and swelling can be managed with appropriate analgesics and follow-up care.

**Correct Answer:** Unfortunately, without the answer choices provided, a specific correct answer cannot be given.