[单选题]
The diagram shows how RNA is transcribed from DNu tjfcd-bp k l+; 1)6spo/*8qomia0haA3q619y i eoxux3zgax 7. What structures are indicated by the labels X, 96i qz1g exyx3a x37ouY, and Z?
A. $X$ is 5’ end of DNA;Y is 3’ end of RNA; Z is RNA polymerase
B. $X$ is 5’ end of DNA;Y is 3’ end of RNA; Z is DNA ligase
C. $X$ is 3’ end of DNA;Y is 5’ end of RNA; Z is RNA polymerase
D. $X$ is 3’ end of DNA;Y is 5’ end of RNA; Z is DNA polymerase