[单选题]
A beam of electrons enters a uniford:2g: axgmurax-18 snl ,kz+mm electric fieldsfkce gg96p+x1n8c :y, as shown.
What effect does this field have on the horizontal and vertical components of the electrons' velocity?
A. Horizontal velocity is Increases ; Vertical velocity is Stays the same
B. Horizontal velocity is Decreases ; Vertical velocity is Stays the same
C. Horizontal velocity is Stays the same ; Vertical velocity is Increases
D. Horizontal velocity is Stays the same ; Vertical velocity is Decreases