I think it's the first and second option but I could be wrong because I don't know much about deserts :)
"<span>The genes for melanin pigmentation remain turned on and prepare more melanin than usual to protect the skin from photo-damage when it is exposed to sunlight for long time" is the actual reason. </span>
The population of the drier island would continue to decrease until only the large beaked finches were the only ones left. The island with plentiful rainfall would have a growing population and most of them would have smaller to medium sized beaks.
In tRNA biosynthesis, ribozymes, which are sub units found in the ribosomes, are essential. hence it is TRUE.
From what I remember it's called a substrate
