Answer:
Option B
Step-by-step explanation:
[tex]\frac{1}{c} +\frac{1}{d} /\frac{c}{d} +\frac{d}{c}\\[/tex]
[tex]\frac{d+c}{c*d} /\frac{c^{2}-d^{2}}{c*d} \\[/tex]
[tex]\frac{(d+c)*c*d}{(c^{2}-d^{2})*c*d}\\[/tex]
Remember Difference of squares: [tex](c^{2} -d^{2} )=(c+d)*(c-d)[/tex]
[tex]\frac{(d+c)*c*d}{(c+d)*(c-d)*c*d}\\[/tex]
[tex]\frac{1}{c-d}[/tex]
