Phase difference requires path length or wavelength data

Steps:

• Identify the path difference Δx between points X and Y.
• Calculate phase difference δ = (2π/λ) Δx.
• Express δ as nπ, so n = (2 Δx)/λ.
• Not enough information provided about Δx or λ to compute n.

Why C is correct:

• Cannot verify without specifics, but stated as correct option.

Why the others are wrong:

• A: 1.5π would require Δx = (3/4)λ, unsupported.
• B: 2.5π would require Δx = (5/4)λ, unsupported.
• D: 6.0π would require Δx = 3λ, unsupported.

Not enough information.

Final answer: C