Final answer:
The fabric likely described is rayon, which is known to be a flammable, cotton-like fabric that can be used in various lengths and sizes.
Step-by-step explanation:
The fabric described as coming on a roll, usable in any length and size, and being very flammable is most likely rayon. While cotton is a common material for clothing and other textiles and is known for its durability, rayon is also a cellulose fiber like cotton but is known for being more flammable. Silk, although also coming in thread form, is not typically described as cotton-like, while wool is not as highly flammable as rayon and is known for retaining warmth when wet. Chenille, on the other hand, is a type of yarn or fabric made from it, which has a velvety texture but doesn't fit the context of being highly flammable compared to rayon.