Blood pressure is the force of blood against the walls of the arteries as the heart pumps it around the body. The normal blood pressure for a healthy adult human is typically 120/80 mmHg. The first number (120) represents the systolic pressure, or the pressure when the heart beats, while the second number (80) represents the diastolic pressure, or the pressure when the heart rests between beats.
Step 1: 140/90.
A blood pressure of 140/90 mmHg is considered to be in the high blood pressure (hypertension) range. Therefore, option (A) is incorrect.
Step 2: 140/100.
A blood pressure of 140/100 mmHg is also considered to be high blood pressure (hypertension), making option (B) incorrect.
Step 3: 120/80.
A blood pressure of 120/80 mmHg is the standard value for normal, healthy blood pressure. Therefore, option (C) is correct.
Step 4: 150/85.
A blood pressure of 150/85 mmHg is considered to be elevated, but not as high as hypertension stage 2. So, option (D) is also incorrect.
Step 5: Conclusion.
The normal blood pressure is 120/80 mmHg. The correct answer is (C).