What type of wool is known for being carded and combed to create a firmer, more durable yarn?

Worsted wool is specifically known for its method of processing, where the fibers are carded and then combed. This procedure aligns the fibers parallel to each other, resulting in a firmer and smoother fabric. The characteristics of worsted wool make it strong and durable, which is ideal for garments that require a resilient texture, such as tailored suits or fine knitwear.

In contrast, cashmere comes from cashmere goats and is celebrated for its softness, but it is not typically processed in the same way to achieve the firmer yarn associated with worsted wool. Merino wool, while also a fine and soft type of wool, generally refers to the fleece from Merino sheep and can be used for different types of yarn processing, including worsted processing, but it’s not defined by that method explicitly like worsted wool is. Acrylic wool is synthetic and does not undergo the same carding and combing processes associated with natural wool fibers, and while it can be durable, it doesn't have the unique qualities of traditional wool.

Thus, worsted wool's specific carding and combing processes lead to its distinctive firmer and more durable yarn characteristics, making it the correct choice in this context.