Because if you have a industrial and agricultural surplus then ultimately the demand for goods would drop as well as the price of that surplus
C) New settlers arrived at a steady rate and the population increased gradually
The answer for this is "Compromise of 1850".
The Compromise of 1850 is a set of laws dealing with the issue of slavery. California was admitted as a free state, upsetting the groups in favor of slavery and satisfying those opposing it in the U.S senate. In Addition, California abolished the slave trade by entering the Union as a free (no slavery) state.
