Question

When California applied for statehood, Southern states feared
a. they would lose equality in the Senate.
b. enslaved workers would escape.
c. they would have to pass new laws to maintain slavery.
d. the gold-mining industry would overtake agriculture.

Answer 1

When California applied for statehood, Southern states feared that "a. they would lose equality in the Senate," since California was to be admitted as a "free" state. 

Answer 2

The correct answer is A. When California applied for statehood, the Southern states feared that they would lose equality in the Senate. Before the admission of California, Southern slavist states and Northern free states had the same number of Senators. But when California was admitted in 1850, it entered into the Union as a free state, so it created a power disbalance for the Southern states, giving to extra votes to the abolitionist states.