Laccoliths are large dome-shaped intrusive bodies with a level base and connected by a pipe-like conduit from below. Lopoliths are formed when the l ava moves upwards, a portion tends to move in a horizontal direction wherever it finds a weak plane and develops into a saucer shape concave to the sky body. Phocoliths are a wavy mass of intrusive rocks found at the base of synclines or the top of the anticline in folded igneous rocks. The near horizontal bodies of the intrusive igneous rocks are called sill or sheet , depending on the thickness of the material. Dykes are formed when the lava makes its way through cracks and solidifies almost perpendicular to the ground. Hence option 1 is incorrect. Calderas are the most explosive volcanoes . When they erupt they tend to collapse on themselves rather than building any tall structure. The collapsed depressions are called calderas.