Final answer:
High blood pressure is known as Hypertension, a condition where the arterial blood pressure is persistently elevated, often leading to serious cardiovascular diseases and known as the 'silent killer.'
Step-by-step explanation:
Hypertension, also known as high blood pressure, is the term used to describe a medical condition where the blood pressure in the arteries is persistently high. It is commonly diagnosed when blood pressure readings consistently exceed 140/90 mm Hg. Hypertension is a major risk factor for many cardiovascular diseases, such as coronary artery disease, stroke, and heart failure, and is often referred to as the "silent killer" because it typically does not show symptoms until significant damage has occurred. Treatment includes lifestyle changes and medication. Among the options provided, the correct answer to what high blood pressure is known as is C) Hypertension.