[单选题]
The reason the positionsvulk 28t )rt a3yj50carx/o 3 of a parti 0)+m3vzjt/e c o5*.wu agwflpcle cannot be specified with infinite precision is thel w*/a f 3p+gj omu5.wtcv0)ze
A. exclusion principle.
B. uncertainty principle.
C. photoelectric effect.
D. principle of relativity.
