In a vertebrate which germ layer forms the skeletal muscle?

Correct! Wrong!

In a vertebrate, the skeletal muscles form from the mesoderm. The mesoderm is one of three germ layers found between the ectoderm and endoderm in triploblastic organisms. Mesoderm also gives rise to the smooth muscle, joints, connective tissue, blood vessels, endocrine glands, bone, cartilage, kidney cortex, urogenital organ, etc.