Which of the following is NOT a common seam allowance measurement used in garment construction?

In garment construction, seam allowances provide the necessary space for stitching two pieces of fabric together while allowing for future adjustments or alterations. The most common seam allowances range from 1/4 inch to 1 inch, with 1/2 inch and 5/8 inch being particularly standard for many home sewing patterns.

A 2-inch seam allowance is considered excessive for most sewing projects. Such a wide allowance may lead to bulky seams and unnecessary fabric usage, which is not practical for garment design. Therefore, while 3/8 inch, 3/4 inch, and 1 inch are typical measurements that allow for clean, finished seams that can support the structure of a garment, a 2-inch seam allowance doesn't fit within the normal conventions of garment construction. This makes it the least realistic choice among the options provided.