Final answer:
The SL1 complex binds to the core promoter for RNA polymerase I.
Step-by-step explanation:
The protein or complex that binds to the core promoter for RNA polymerase I is the SL1 complex.
TFIIIB is a transcription factor complex that binds to the promoter for RNA polymerase III, not RNA polymerase I.
UBF is a protein that binds to the upstream control element (UCE) and the core promoter of RNA polymerase I, but it does not directly bind to the core promoter for RNA polymerase I.
TFIIA is a basal transcription factor that helps to stabilize the pre-initiation complex, but it does not directly bind to the core promoter for RNA polymerase I.
Brf is a transcription factor that plays a role in transcription initiation by RNA polymerase III, not RNA polymerase I.