Answer:
B.
Step-by-step explanation:
1) if sinθ<0, then θ can be in quadrants III or IV;
2) if according to the condition cosθ=3/5>0, then θ can be in quadrants I or IV;
3) if cosθ>0 and sinθ<0, then θ is in quadrant IV;
4) sinθ can be calculated (the required sin in quadrant IV is less zero):
[tex]sinO=- \sqrt{1-cos^2O}=- \sqrt{\frac{16}{25}}=- \frac{4}{5} .[/tex]
