What are the respective roles of distal and proximal control elements?
a. Distal control elements regulate gene expression from a distance by interacting with enhancer elements.
b. Proximal control elements regulate gene expression by interacting with the promoter region of a gene.
c. Distal control elements can regulate multiple genes at once, while proximal control elements typically regulate a single gene.
d. Proximal control elements are more directly involved in the initiation of transcription, while distal control elements play a more regulatory role in gene expression.