The correct option is D Porous body
A. Diploblastic animals are those which have two germ layers, ectoderm and endoderm. Such animals have tissue level of organisation. Sponges have a cellular level of organisation and hence, ectoderm and endoderm are not there. Instead, body wall consists of two layers, pinacoderm and choanoderm with a non-cellular mesenchyme in between.
B. Sponges may be marine or freshwater. Most sponges are marine.
C. Sponges do not form any link between the living and non-living organisms.
D. Sponges have a porous body. The body is covered by numerous pores called ostia through which water enters the body of sponges and a single pore called osculum through which water flows out of the body.
Such a porous body is a characteristic feature of sponges.
So, the correct answer is 'Porous body'.