The determinant equals

We have,

Taking (b – a) common from C₁ and C₃, we get

Applying C₁→ C₁ – C₃, we get

If any two columns (or rows) of a determinant are identical (all corresponding elements are same), then the value of determinant is zero.

Here, C₁ and C₂ are identical.

Hence, the correct option is (d).