During transcription, RNA polymerase holoenzyme binds to a gene promoter and assumes a saddle-like structure. What is its DNA-binding sequence?

The promoter is the DNA sequence located towards the upstream end of the structural gene that provides the binding site for RNA polymerase.
The promoter contains a short conserved sequence rich in adenine and thymine, called the TATA box (the Pribnow box, TATAAT, in prokaryotes and the Hogness box, TATAAA, in eukaryotes).
The RNA polymerase holoenzyme, with the help of the sigma factor in prokaryotes or the TATA-binding protein in eukaryotes, recognises and binds to this TATA sequence.
The protein sits astride the DNA like a saddle on this sequence and bends the DNA.
The A-T rich region has only two hydrogen bonds per base pair, so the strands separate easily here and transcription can begin.
So the DNA-binding sequence is TATA, as also stated in the solution of the source.