Which of the following states bernoulli’s principle? a. as the speed of a fluid decreases, the pressure within the fluid decreases. b. as speed of a fluid increases, the pressure within decreases. c. as the speed of a fluid changes, the pressure of the fluid remains constant. d. none of the above

The correct answer is B. As speed of a fluid increases, the pressure within decreases.
Using formulas, Bernoulli's principle can be written as 

where p is the pressure of the fluid,  its density, v its speed, and h its elevation above a reference level.
Assuming h does not change, we can see that if the speed v increases, the pressure p must decrease in order  to keep constant the sum of the three terms.