**Core Concept**
The question involves a pharmacological interaction between a tricyclic antidepressant (TCA) and a drug 'X', resulting in the abolition of the antihypertensive action of 'X'. This interaction is related to the blockade of adrenergic receptors, which are targeted by certain antihypertensive drugs.

**Why the Correct Answer is Right**
Tricyclic antidepressants, such as Amitriptyline, block alpha-1 adrenergic receptors peripheralally, which leads to vasodilation and a subsequent decrease in blood pressure. If 'X' is a centrally acting antihypertensive drug, such as clonidine, which primarily acts by stimulating alpha-2 adrenergic receptors in the CNS to decrease sympathetic outflow, the abolition of its antihypertensive action by a TCA would be due to the blockade of these receptors by the TCA, thereby reducing its effect on blood pressure.

**Why Each Wrong Option is Incorrect**
**Option A:** Drugs like ACE inhibitors, such as Enalapril, work by inhibiting the conversion of angiotensin I to angiotensin II, which has no direct relation to the blockade of adrenergic receptors by TCAs.
**Option B:** Beta-blockers, such as Propranolol, primarily act by blocking the effects of epinephrine on beta-adrenergic receptors, which is not directly related to the interaction between TCAs and centrally acting antihypertensive drugs.
**Option C:** Diuretics, such as Furosemide, work by increasing urine production, which is not directly affected by the blockade of adrenergic receptors by TCAs.

**Clinical Pearl / High-Yield Fact**
When prescribing a TCA, it is essential to consider potential interactions with other centrally acting antihypertensive drugs, such as clonidine, which may lead to loss of antihypertensive efficacy.

**Correct Answer:** C. Clonidine.