How does the modern theory of evolution explain the loss of vestigial organs? how does the modern theory compare with lamarck's theory of "use and disuse? "

Modern theory of evolution explains that "organisms change over time as a result of changes in heritable physical or behavioral traits". Hence this change suggests the loss of vestigial organs.

Explanation:

Vestigial organ are those which do not have any function but is present in our body.According to the modern theory the genetic and physical appearance changes along with the adaptation in environment by the organism.So if the organ looses its function in order to sustain and adopt in the changing environment then they become vestigial and slowly disappear.This is the common example for the Lamarck's theory of "use and disuse".