Answer: Option C
Explanation:
A waterbed, water mattress, or flotation mattress is a bed or mattress filled with water. Waterbeds intended for medical therapies appear in various reports through the 19th century. The modern version, invented in San Francisco and patented in 1971, became an extremely popular consumer item in the United States through the 1970s.
Advantage :
The bed shapes exactly to the body, thus minimizing pressure, especially around the joints. Waterbeds remove pressure from the spine allowing the spinal muscles to fully relax. This can aid in the treatment of back pain for some individuals.In paralytic or movement-impaired people they can reduce the risk of bedsores.
It is impossible for dirt and dead skin particles to penetrate the water mattress, which can then be wiped periodically with a cloth and vinyl cleaner. The cover over the mattress can be regularly washed - thus virtually eliminating house dust mites in the bed. Dust mites can trigger asthma, eczema, and allergies in people sensitive to them.
