Name the three main types of relief sculptures. which do you think would be the most difficult to create? why?

There are three basic types of relief sculpture: (1) low relief  where the sculpture projects only slightly from the background surface; (2) high relief  where the sculpture projects at least half or more of its natural circumference from the background, and may in parts be wholly disengaged from the ground, thus approximating sculpture in the round. [Sculptors may also employ middle-relief , a style which falls roughly between the high and low forms]; (3) sunken relief, where the carving is sunk below the level of the surrounding surface and is contained within a sharpely incised contour line that frames it with a powerful line of shadow. The surrounding surface remains untouched, with no projections. Sunken relief carving is found almost exclusively in ancient Egyptian art, although it has also been used in some beautiful small-scale ivory reliefs from India.