To solve this problem, we need to identify the enzyme responsible for opening the DNA helix during transcription. Let's analyze each option:$\newline \bullet$DNA helicase:$\newline$ - DNA helicase is an enzyme that unwinds the DNA double helix during DNA replication, not transcription.$\newline$ - Therefore, this is not the correct enzyme for transcription.$\newline \bullet$DNA polymerase:$\newline$ - DNA polymerase is an enzyme that synthesizes DNA molecules from deoxyribonucleotides, the building blocks of DNA.$\newline$ - It is involved in DNA replication, not transcription.$\newline \bullet$RNA polymerase:$\newline$ - RNA polymerase is the enzyme that synthesizes RNA from a DNA template during transcription.$\newline$ - It facilitates the unwinding of the DNA helix to allow the synthesis of RNA.$\newline$ - This is the correct enzyme for transcription.$\newline \bullet$DNA ligase:$\newline$ - DNA ligase is an enzyme that joins DNA strands together by forming phosphodiester bonds.$\newline$ - It is involved in DNA replication and repair, not transcription.$\newline$Therefore, the enzyme that facilitates the opening of the DNA helix during transcription is RNA polymerase.$\newline$This corresponds to Option 3.