Step 1: Understanding the Concept
Blended fabrics combine properties of natural and synthetic fibres.
Step 2: Terycot
Terycot (terene cotton) is made by blending cotton with terylene, the polyester also known as Dacron.
Step 3: Compare the options
Nylon 6 and nylon 6,6 are polyamides and polyacrylonitrile is used as artificial wool, so they do not form terycot.
Final Answer:
Dacron (a polyester) is blended with cotton to form terycot.
\[ \boxed{\text{(A) }\text{Dacron}} \]