By a large margin, which group made up the majority of california's population in 1840? a. russian traders b. irish immigrants c. spanish convicts d. native americans

By a large margin, Native Americans made up the majority of California's population in 1840.  Option D is correct.

The Population of Native Californian makes reference to the population of Indigenous peoples of California. Estimates before and after European contact have changed substantially. Pre-contact estimates range from 133,000 to 705,000 with some recent scholars concluding that these estimates are low.

After the arrival of Europeans in California, disease and violence reduced the population to as low as 25,000.