The process of translation of mRNA to proteins begins as soon as :
The larger subunit of ribosome encounters mRNA
Both the subunits join together to bind with mRNA
The tRNA is activated and the larger subunit of ribosome encounters mRNA
The small subunit of ribosome encounters mRNA
When the smaller submit of ribosome encounter m-RNA, the process of translation of m-RNA to protein begins. This process is followed by the binding of a larger subunit. The activated t-RNA molecule carrying the amine acid methionine binds to the start codon of the mRNA sequence.
Hence, the correct option is (4).