At First, thE ______ oF Color piCturEs ovEr A long DistAnCE sEEmED impossiBlE, But, with pAinstAking EFForts AnD At grEAt ExpEnsE, it BECAmE A rEAlity.
A．trAnsACtion
B．trAnsmission
C．trAnsFormAtion
D．trAnsition