Final answer:
After a eukaryotic mRNA is exported from the nucleus, the correct process that occurs is that the ribosome binds to the mRNA. This forms the initial step in protein synthesis within the cytoplasm.
Step-by-step explanation:
After a eukaryotic mRNA is exported from the nucleus, the ribosome binds to the mRNA. This happens in the cytoplasm where translation begins. The mature mRNA that has been exported has already undergone several processing steps inside the nucleus, which include the addition of a 5' methylguanosine cap, splicing to remove introns and ligate exons, and the addition of a poly-A tail at its 3' end. These modifications protect the mRNA from degradation and facilitate its export from the nucleus.
Once in the cytoplasm, the small ribosomal subunit binds to the 5' cap of the eukaryotic mRNA, which is a critical step in the initiation of translation. The ribosome then scans for the start codon AUG to begin translating the mRNA into a polypeptide chain. This process is known as protein synthesis. Therefore, the answer to the student's question is A. the ribosome binds to the mRNA.