Herbarium houses dried, pressed and preserved plant specimens.
Key is a taxonomic aid for identification of specimens.
Botanical gardens have collection of living plants for reference.
A museum has collection of photographs of plants and animals.
The herbarium is a collection of preserved plant specimens, which may be a whole plant or plant parts, usually be in a dried form mounted on a sheet. Botanical gardens are the establishment, where plants are grown for the display to the public and often for scientific study. The museum is a building in which objects of historical, scientific, artistic or cultural interest are stored and exhibited. A dichotomous key is a list of paired statements that guide to the identification of a species. So, the correct answer is option D.