Let's begin with this one. So we have glycine and tryptophan. We have glycine and then we have tryptophan. Now, to find out what comes next, we have to go to this experiment one. So we have glycine tryptophan, and the only time we have glycine tryptophan here is in this fragment one glycine tryptophan. Now, this third amino acid basically tells us which fragment must be connected to this one.