Why did the Land Law of 1851 cause most Californios to lose their land?
A. The law provided forty-niners and others in the gold rush the
right to take the Californios' land.
B. The law made the Californios prove that they owned the land
and most could not.
C. The land was owned by The Bear Flag Republic.

c

Explanation:

The California Land Act of 1851 (9 Stat. 631), enacted following the Treaty of Guadalupe Hidalgo and the admission of California as a state in 1850, established a three-member Public Land Commission to determine the validity of prior Spanish and Mexican land grants.

hope this helps

the answer is states.