**Core Concept**
Surya kant is prescribed with a first-generation antihistamine, which is a type of medication used to treat allergic reactions. First-generation antihistamines work by blocking histamine receptors in the brain, but they can also cross the blood-brain barrier and cause central nervous system (CNS) side effects.

**Why the Correct Answer is Right**
First-generation antihistamines, such as diphenhydramine, can cause drowsiness, dry mouth, and blurred vision due to their ability to cross the blood-brain barrier. They can also impair cognitive function and increase the risk of falls in elderly patients. Additionally, first-generation antihistamines can cause sedation and impair driving ability. Surya kant should be advised to avoid operating heavy machinery or driving while taking this medication.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the side effects of first-generation antihistamines.
* **Option B:** While first-generation antihistamines can cause dry mouth, this is not the most significant concern for Surya kant.
* **Option C:** First-generation antihistamines are not typically associated with an increased risk of peptic ulcers.

**Clinical Pearl / High-Yield Fact**
First-generation antihistamines are not recommended for patients with glaucoma, as they can increase intraocular pressure. Additionally, patients taking first-generation antihistamines should be advised to avoid consuming alcohol, as it can exacerbate CNS side effects.

**Correct Answer:** D. operating heavy machinery or driving