Step 1: Concept
The determinant of a triangular matrix is the product of its diagonal elements.
Step 2: Meaning
The matrix is lower triangular (all elements above main diagonal are 0).
Step 3: Analysis
$Det = 1 \times (x+2) \times (x+3) = 0$.
Step 4: Conclusion
$x+2 = 0 \implies x = -2$; $x+3 = 0 \implies x = -3$.
Final Answer: (C)