Which organization hosts the Chelsea Flower Show?

The Chelsea Flower Show is hosted by the Royal Horticultural Society (RHS), a prestigious gardening charity in the UK that promotes horticulture and gardening. The RHS organizes this renowned annual event in Chelsea, London, which showcases some of the finest gardens and horticultural displays from around the world. The society's dedication to promoting horticultural excellence and education is evident in the high caliber of the show, which attracts both professional and amateur gardeners, as well as a wide audience of horticulture enthusiasts.

The other organizations mentioned do not have a direct connection to the Chelsea Flower Show. The Royal Society for the Protection of Birds focuses on bird conservation, the Royal Institute of British Architects is involved with architecture, and the Royal Parks Foundation supports London's Royal Parks. None of these organizations are dedicated to horticulture in the way that the RHS is, which makes the Royal Horticultural Society the correct choice for hosting this iconic event.