The Southern California Batholith mainly consists of which of the following rocks?

The Southern California Batholith is primarily composed of intrusive igneous rocks, and among the options provided, quartz diorite and granite are the most representative of the batholith's main lithological components.

Quartz diorite is characterized by a mix of biotite, hornblende, and quartz, which gives it distinct mineralogical properties, making it a typical rock type found in this batholith. Granite is likewise a significant component, composed mainly of quartz, feldspar, and mica, and is pervasive in the batholith, especially in its upper parts.

The presence of both quartz diorite and granite reflects the varied stages of magmatic activity and different cooling histories that have influenced the formation of the batholith. This aligns well with geological observations made by geologists studying the region, confirming the predominance of these rock types in Southern California's geological framework.

Other options list rock types that do not represent the main constituents of the Southern California Batholith, such as gabbro, which are typically formed in different tectonic settings, quartz monzonite which may occur but is less dominant, and limestone, which is a sedimentary rock not characteristic of the batholith. Thus, quartz diorite and granite are