Which dermal layer is responsible for the dermal properties of skin that are evident as cleavage lines? which dermal layer is responsible for the dermal properties of skin that are evident as cleavage lines? the papillary layer the reticular layer the basal layer the granular layer?

a "theory" a suggestion that is not 100 % accurate, or a figure. some people say its a theory because they of all the passed theory's about one subject. it depends sometimes theory might be accurate and sometimes they are.

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".