The equation of the tangent at the point (x', y') to the ellipse \(\frac{{{x^2}}}{{{a^2}}} + \frac{{{y^2}}}{{{b^2}}} = 1\) is:

• A. \(\frac{{xx'}}{{{a^2}}} + \frac{{yy'}}{{{b^2}}} = 1\)
• B. \(\frac{{x - x'}}{a} + \frac{{y - y'}}{b} = 1\)
• C. \(\frac{{x(x - x')}}{{{a^2}}} + \frac{{y(y - y')}}{{{b^2}}} = 1\)
• D. \(\frac{{{{(x')}^2}}}{{{a^2}}} + \frac{{{{(y')}^2}}}{{{b^2}}} = 1\)