Answer: D) regulate transcription, bind specific DNA sites, and can be influenced by small molecules.
Step-by-step explanation:
Regulatory protein (gene-regulatory protein) are the proteins which affects DNA molecular regions transcribed by RNA polymerase during the transcription process. These proteins include transcription factors, which help to regulate protein synthesis in cells.
Proteins bind to different DNA sequences within or near to a gene and facilitate or suppress its transcription into an RNA. They can directly bind to specific DNA "promoter" regions, which are located in a gene upstream of the coding region, or directly to the molecule of RNA polymerase and the process is influence by several other enzymes as well.
Hence, the correct option is D.