The correct answer is: B. stagnation pressure.
A pitot tube is a device used to measure the stagnation pressure of a fluid. It consists of a tube with a small opening facing the oncoming fluid, and a second opening perpendicular to the first. The stagnation pressure is the pressure at the point where the fluid comes to a complete stop, and it is equal to the sum of the static pressure and the dynamic pressure.
The static pressure is the pressure of the fluid at rest. It can be measured by a simple pressure gauge. The dynamic pressure is the pressure due to the motion of the fluid. It can be calculated from the Bernoulli equation, which states that the total energy of a fluid is constant.
The pitot tube is used in a variety of applications, including aircraft flight measurement, wind tunnel testing, and hydraulics.
A. velocity at stagnation point is incorrect because the pitot tube measures the stagnation pressure, not the velocity.
C. static pressure is incorrect because the pitot tube measures the stagnation pressure, not the static pressure.
D. dynamic pressure is incorrect because the pitot tube measures the stagnation pressure, not the dynamic pressure.