Final answer:
The complex called a spliceosome is responsible for removing introns from the primary RNA transcript during splicing in eukaryotic cells.
Step-by-step explanation:
The large multi-protein and RNA complex that binds to the primary transcript and participates in splicing out the introns is called the spliceosome. Pre-mRNA splicing, which involves the precise removal of introns from the primary RNA transcript, is catalyzed by protein complexes known as spliceosomes. These complexes are composed of proteins and RNA molecules called small nuclear RNAs (snRNAs), which recognize the sequences at the 5' and 3' ends of the intron, facilitating the splicing process.