In the Rearrangement of 2-Butyne to 1-Butyne, What Causes the Reaction

In the rearrangement of 2-butyne to 1-butyne, what causes the reaction to go to completion?

A) the increased stability of the terminal triple bond in the product
B) the high pK_a of ammonia versus the methyl group in 2-butyne
C) the decreased activation energy for conversion of the allene intermediate to 1 -butyne
D) the much lower pK_a of the acetylenic proton in the product versus the other species
E) the increased stability of the 1,2 -butadiene intermediate versus 2 -butyne