Select the correct statement below:

A$.$ More than a single pledge may not exist at the same time over the same thing and the transfer of control is an essential element of a pledge.

B$.$ Many pledges may exist at the same time over the same thing and the transfer of control is an essential element of a pledge.

C$.$ More than a single pledge may not exist at the same time over the same thing and no control is needed over a pledge.

D$.$ Pledges are a subset of agency agreements.