**Core Concept**
Hypertension is a multifactorial disease influenced by both modifiable and non-modifiable risk factors. Non-modifiable risk factors are characteristics that cannot be changed or altered, whereas modifiable risk factors can be modified through lifestyle changes or medical interventions.

**Why the Correct Answer is Right**
The correct answer is age. As individuals age, their risk of developing hypertension increases due to physiological changes that occur with aging, such as decreased renal function, increased vascular stiffness, and changes in the renin-angiotensin-aldosterone system. These changes lead to increased peripheral resistance and blood pressure. The renin-angiotensin-aldosterone system plays a crucial role in regulating blood pressure, and alterations in this system contribute to the development of hypertension.

**Why Each Wrong Option is Incorrect**
**Option A:** Family history is a modifiable risk factor, as an individual's genetic predisposition can be influenced by lifestyle choices and environmental factors.
**Option B:** Obesity is a modifiable risk factor, as weight loss and dietary changes can reduce the risk of developing hypertension.
**Option C:** Smoking is a modifiable risk factor, as quitting smoking can significantly reduce the risk of developing hypertension.

**Clinical Pearl / High-Yield Fact**
Aging is a significant risk factor for hypertension, and the risk increases exponentially with age. The 10-year risk of developing hypertension is approximately 90% in individuals over the age of 80.

**Correct Answer:** D. Age