Which of the following position had the most unpredictable outcome?
Stephen Douglas used popular sovereignty to get the territory settled as quickly as possible. The reason there was so much fighting in Kansas was that Douglas left the question of slavery to be decided by the settlers. That is not a clear answer. Each of the other options is more definite:
For slavery (B), against all slavery (D), against slavery in the West (A), or for getting rid of slavery by having children of slaves become free at the age of 21 after a certain date (E).