In this task, you are given a context, a subject, a relation, and many options. Based on the context, from the options select the object entity that has the given relation with the subject. Answer with text (not indexes).

Context: Prokaryotes require the use of three initiation factors: IF1, IF2, and IF3, for translation., Initiation factors are proteins that bind to the small subunit of the ribosome during the initiation of translation, a part of protein biosynthesis., Prokaryotic initiation factor - 3 is a prokaryotic initiation factor . IF3 is not universally found in all bacterial species but in E. coli it is required for the 30S subunit to bind to the initiation site in mRNA . In addition , it has several other jobs including the stabilization of free 30S subunits , enables 30S subunits to bind to mRNA and checks for accuracy against the first aminoacyl - tRNA . It also allows for rapid codon - anticodon pairing for the initiator tRNA to bind quickly to . IF3 is required by the small subunit to form initiation complexes , but has to be released to allow the 50S subunit to bind ., Subject: prokaryotic initiation factor-3, Relation: instance_of, Options: (A) protein (B) three
protein