• Cross-Dyeing and Solid-Shade Dyeing of Fiber Blends:
• Assertion (A): It is possible to dye textiles containing fibres having different dye affinity, with one solid colour using a single dye bath. $\implies$ Correct.
• In blend dyeing (e.g., polyester/cotton or wool/acrylic blends), union dyeing produces a uniform solid shade throughout the fabric from a single dye bath containing compatible dye classes.
• Reason (R): Dyes having affinity for different fibre types can be used to produce one solid colour. $\implies$ Correct.
• By formulating a combination of disperse dyes (for polyester) and reactive dyes (for cellulose) tailored to each fiber component's specific chemical affinity, both components absorb their respective chromophores at equal visual depths, yielding a solid uniform color.
• Conclusion: Both (A) and (R) are correct and (R) is the correct explanation of (A) (Option 1).

Correct option: (1) Both (A) and (R) are correct and (R) is the correct explanation of (A).