Answer:
C
Step-by-step explanation:
The state that was admitted to the Union as the 16th free state is C. California.
The state that was admitted to the Union as the 16th free state was California. California was admitted to the Union on September 9, 1850, as the 31st state and the first free state to be carved out of the former Mexican territory. California's admission was part of a compromise between Northern and Southern states in Congress, known as the Compromise of 1850, which allowed California to be admitted as a free state, while also enacting stricter fugitive slave laws and allowing the territories of Utah and New Mexico to decide the issue of slavery for themselves. The admission of California as a free state was significant in the lead-up to the American Civil War, as it tipped the balance of power in Congress in favor of the free states.