[单选题]
Vector $d$ makes an angle $\theta$ with the horizontal as shown. Its magnitude is 5m and the magnitude of its horizontal component $d_x$ is 3m.
Which of the following is correct about the magnitude and direction of its vertical component?
A. Magnitude is 4m Direction is Up
B. Magnitude is $\sqrt{34}m$ Direction is Up
C. Magnitude is $\sqrt{34}m$ Direction is Down
D. Magnitude is 4m Direction is Down
