**Core Concept**
The patient's altered sensorium, tremors, increased deep tendon reflexes (DTR's), incontinence of urine, and serum lithium level of 1.95 mmol/L suggest lithium toxicity. Lithium is a narrow therapeutic index medication, and even slight increases in serum levels can lead to toxicity.

**Why the Correct Answer is Right**
Lithium toxicity occurs when the serum level exceeds 1.5 mmol/L. The patient's symptoms, including altered sensorium, tremors, and increased DTR's, are consistent with lithium toxicity. The episode of severe gastroenteritis may have contributed to the increased serum lithium level due to dehydration and reduced renal clearance. In addition, the patient's recent history of epileptic fits may indicate a pre-existing seizure disorder, which could be exacerbated by lithium toxicity.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not provided.
* **Option B:** This option is not provided.
* **Option C:** This option is not provided.
* **Option D:** This option is not provided.

**Clinical Pearl / High-Yield Fact**
Lithium toxicity can be treated with hemodialysis, which should be considered in patients with serum levels above 2.5 mmol/L or those with severe symptoms. It is essential to monitor serum lithium levels regularly in patients on lithium therapy.

**Correct Answer:** A. (Note: The question doesn't provide options, so I'm assuming A, B, C, D are the options. Please provide the actual options to get a correct explanation.)