Let △ABC be a given triangle. If ∣BA−tBC∣≥∣AC∣ for any t∈R, then △ABC is
<spanclass=′latex−bold′>(A)</span>an acute triangle<spanclass=′latex−bold′>(B)</span>an obtuse triangle<spanclass=′latex−bold′>(C)</span>a right triangle<spanclass=′latex−bold′>(D)</span>not known