Step 1: Analysis
Simplify the denominator using the identity $(a+b)(a-b) = a^2 - b^2$:
$[(1 + \sin \alpha) + \cos \alpha][(1 + \sin \alpha) - \cos \alpha] = (1 + \sin \alpha)^2 - \cos^2 \alpha$.
Step 2: Calculation
$(1 + \sin^2 \alpha + 2 \sin \alpha) - \cos^2 \alpha$.
Since $1 - \cos^2 \alpha = \sin^2 \alpha$, the denominator becomes $\sin^2 \alpha + \sin^2 \alpha + 2 \sin \alpha = 2 \sin^2 \alpha + 2 \sin \alpha$.
Step 3: Conclusion
Denominator $= 2 \sin \alpha (1 + \sin \alpha)$.
Since the numerator is also $2 \sin \alpha (1 + \sin \alpha)$, the ratio is 1.
Final Answer: (C)