If the voltage of this battery was increased, what would happen to the light bulb’s brightness

Surprisingly, nothing.

Without changing the characteristics of the light bulb, it's not actually possible to change the voltage without changing the current as well. When the voltage is increased, the current through the bulb has to increase as well in order to make it glow brighter.

50% lit on the left side

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.