The Contestant Changes Buckets from the Original Bucket to the Other

The contestant changes buckets from the original bucket to the other bucket remaining. This change of buckets changes the probability that the contestant will win the 5-oz. gold bar from _____________.

A) $\frac { 1 } { 3 }$ to $\frac { 1 } { 2 }$
B) $\frac { 1 } { 2 }$ to $\frac { 1 } { 3 }$
C) $\frac { 1 } { 2 }$ to $\frac { 2 } { 3 }$
D) $\frac { 1 } { 3 }$ to $\frac { 2 } { 3 }$
E) $\frac { 2 } { 3 }$ to $\frac { 1 } { 3 }$