One of the biggest challenges for the exploration and future colonization of space is the expense of launching materials from Earth. Current rocket propulsion technology makes launches very expensive. Every item launched into space must be considered carefully because the expense goes up with every extra pound of cargo.

This problem would be best solved with
A.
heavier, more durable rockets and launching methods that are less cost-efficient.
B.
launching methods that are more cost-efficient and cargo made of lighter materials.
C.
heavier, more durable rockets and launching methods that are more cost-efficient.
D.
launching methods that are more cost-efficient and cargo made of heavier materials.

answer and explanation;

volcanic rocks are igneous rocks which form from lava, molten rock which has been thrust out of a volcano onto the surface of a rocky body such as an asteroid, planet, or dwarf planet.  

plutonic rocks are igneous rocks which form from subterranean chambers of molten rock or magma. plutonic rocks make up the base of continental crust as well as oceanic crust. their slow rate of formation causes them to be coarse grained since there is plenty of time for large crystals to form before the magma solidifies into rock.

the textural difference is that plutonic rocks are more coarse grained than volcanic rocks. plutonic rocks are coarse grained while volcanic are fine grained ; glassey or fragmental. since fine and coarse are adjectives the decision as to whether a rock is fine or coarse grained is generally made on the bases of whether or not the individual crystals can be seen in most if the rock.