If sec θ – tan θ = x/y, (0 < x < y) and 0°< θ < 90°, then sinθ is equal to:

• A. \(\frac{{{y^2} - {x^2}}}{{{x^2} + {y^2}}}\)
• B. \(\frac{{{x^2} + {y^2}}}{{{y^2} - {x^2}}}\)
• C. \(\frac{{2xy}}{{{x^2} + {y^2}}}\)
• D. \(\frac{{{x^2} + {y^2}}}{{2xy}}\)