[单选题]
A ball is thrown with a velocity of 20 m/s at an angledq jrsgo/ huuc91;:5 spo/bf3 of 60jdx-07vhn sjjr r/l7/e above the horizontal. What is the horizontal com j 7/h0v/sjrr j-xlnd7ponent of its instantaneous velocity at the exact top of its trajectory?
