The blood buffer reactions described by H₂CO₃
<--------> H⁺ + HCO₃- indicate that

A)scientists are uncertain which direction the equation flows.
B)the reaction can flow either direction depending on whether there is too much H⁺ or more H⁺ is needed.
C)any reaction in one direction causes an immediate reverse reaction.
D)chemicals can swing wildly from acidic to basic.
E)the reaction goes back and forth in an unpredictable manner.