Concept:Use the formula for adding fractions: ba+dc=bdad+bc and the identity sin2x+cos2x=1.Explanation:Step 1: Write the sum with a common denominator:1+sinxcosx+1+cosxsinx=(1+sinx)(1+cosx)cosx(1+cosx)+sinx(1+sinx).Step 2: Expand the numerator:cosx+cos2x+sinx+sin2x.Step 3: Rearrange terms:(sin2x+cos2x)+(sinx+cosx).Step 4: Use sin2x+cos2x=1 to get:1+sinx+cosx.Step 5: Place over the common denominator:(1+sinx)(1+cosx)1+sinx+cosx.Answer:(1+sinx)(1+cosx)cosx+sinx+1 (Option D)