Task: Question Answering
Input (English): Question: In relation to the structure of the genomes, the introns: 
 Options:  <1> They frequently occur in prokaryotic genomes. <2> There may be several in the same gene. <3> They encode rare amino acids in proteins. <4> They are transcribed and translated. <5> They have a high content in G: C pairs.
Output (English): 2