Question

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Ultrasound can be used to measure the velocity of blood flow in the ascending aorta by the application of the Doppler principle.
Reason (R) : If the area of cross-section of the aorta is known, the blood flow can be calculated as follows :-
Blood flow = $\frac{\text{velocity} \times \text{stroke} - \text{volume}}{\text{area}}$
In the light of the above statements, choose the most appropriate answer from the options given below :

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
• B. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
• C. (A) is correct but (R) is not correct
• D. (A) is not correct but (R) is correct

Hint:

Always check the units in formulas! Flow rate ($Q$) is measured in $cm^3/sec$ (or $mL/sec$). Velocity is $cm/sec$. Area is $cm^2$. Therefore, $cm/sec \times cm^2 = cm^3/sec$. Dividing by area as shown in (R) would yield $1/sec$, proving the formula is fake.

Answer 1

The Correct Option is C