In most vertebrates, the common basic plan with a skull, vertebral column and a pair of girdle is an evidence of evolution from

Comparative anatomy is the study of similarities and differences in the body structures of different species. When most vertebrates share a common basic structural plan consisting of a skull, a vertebral column, and a pair of limb girdles (pectoral and pelvic), this provides strong evidence that they descended from a common ancestor. These shared structures are called homologous structures.

Homologous structures have the same fundamental design and embryonic origin but may be modified for different functions in different species. For example, the forelimb of a human (arm), a whale (flipper), a bat (wing), and a horse (leg) all contain the same set of bones - humerus, radius, ulna, carpals, metacarpals, and phalanges - arranged in the same basic pattern, even though they serve very different purposes. This shared blueprint points to a common evolutionary ancestor.

The other options represent different lines of evolutionary evidence:

• Fossil records provide evidence of organisms that lived in the past, showing how body forms have changed over geological time.
• Molecular records compare DNA, RNA, or protein sequences across species to determine evolutionary relatedness.
• Embryology examines similarities in the early developmental stages of different organisms (e.g., pharyngeal pouches in vertebrate embryos).

The question specifically describes structural similarities in adult body plans across living vertebrates, which falls squarely under comparative anatomy.