Which of the following steps is crucial for the small ribosomal subunit to locate the start codon on the mRNA?

• A. Binding of the release factors to the mRNA
• B. Scanning of the mRNA from the 5' end until the start codon is reached
• C. Binding of the large ribosomal subunit to the mRNA
• D. Cleavage of the mRNA by ribonucleases

Answer: (B)