Why are Northerners and Southerners so anxious and tight about new territories applying for statehood?

Related to the slave state and free state

Explanation:

The North and South states were anxious about new territories because they feared the balance of the states in America. Both worried the states favouring slavery and those opposing slavery. The North and the South wanted to hold the stability of power in the Senate by balancing the powers. Many of the Southern wanted to gain the upper hand on the issue of slavery.

answer; i believe the above statement is (true);

answer; ///i do believe that the correct answer is (b) ///middle colony