21. A soft sedimentary rock, like limestone, can change over time into a hard metamorphic rock like marble. What processes must have acted on the limestone over the years to change this
sedimentary material into hard metamorphic material?

The heat generated by the magma chamber has changed these sedimentary rocks into the metamorphic rocks marble, quartzite, an hornfels. Regional Metamorphism occurs over a much larger area. This metamorphism produces rocks such as gneiss and schist. ... They are generally as hard and sometimes harder than igneous rocks.

the answer is c

explanation:

an organism's phenotype is the  form of a trait  that it  displays. for  flowercolor, a pea  plant  can  display  a phenotype of purple or white flowers. an organism's  genotype  is the alleles of a gene it contains. based on his data, mendel concluded that a phenotype can be  determined  by more than one  genotype.