Concept:
Religious traditions often influence textile design and construction. Mashru is a clever technical solution to a religious dietary/dress law.
Step 1: Analyze the cultural context (Assertion A).
In Islamic tradition, wearing pure silk directly against the skin is considered a luxury forbidden for men. To solve this, the Mashru fabric was developed. The word "Mashru" literally means "permitted" in Arabic. It allowed men to enjoy the luster of silk on the outside while only cotton touched their skin. Assertion (A) is correct.
Step 2: Analyze the technical construction (Reason R).
Mashru is a warp-faced fabric. It uses silk warp and cotton weft. By using a Satin weave (where the warp floats over multiple weft threads), the silk warp dominates the top surface of the fabric, while the cotton weft remains on the underside. Reason (R) is correct.
Step 3: Evaluate the link.
The specific satin-weave construction (Reason) is exactly what creates the "silk outside, cotton inside" property that makes the fabric "permitted" or Mashru (Assertion). Therefore, (R) is the correct explanation for (A).