Which three statements correctly describe the process that takes place before a mature mrna exits the nucleus?

After transcription begins, several steps must be completed before the fully processed mRNA is ready to be used as a template for protein synthesis in the ribosomes; this may be described by; A cap consisting of a modified guanine nucleotide is added to the 5' end of the pre-mRNA.; A poly-A tail of about 50 to 250 adenine nucleotides is added to the 3' end of the pre-mRNA, and also the Non-coding sequences called introns are spliced out by molecular complexes called spliceosomes.