Why was Pluto classified as not a planet

the international astronomical union (IAU) downgraded the status of pluto to that of a dwarf planet because it did not meet the three criteria the IAU uses to define a full-sized planet essentially pluto meets all the criteria except one it  has not cleared its neighboring region of other objects

a. to encourage apoptosis

igneous rocks which formed by the crystallization of magma at the surface of the earth called extrusive rocks. they are characterized by fine-grained textures because the rapid cooling at or near the surface did not provide enough time for large crystals to grow.