The Yeast Genome Was Sequenced More Than 20 Years Ago

The yeast genome was sequenced more than 20 years ago, yet the total number of genes continues to be refined.The sequencing of closely related yeast species was important for validating the identity of short (less than 100 nucleotides long) open reading frames (ORFs) that were otherwise difficult to predict.What is the main reason that these short ORFs are Difficult to find without the genomes of other yeast for comparison?

A) Short ORFs are found only in yeast.
B) The short ORFs code for RNAs.
C) Many short stretches of DNA may lack a stop codon simply by chance, making it difficult to distinguish those DNA sequences that code for proteins from those that do not.
D) Short ORFs occur mainly in gene-rich regions, making them difficult to identify by computer programs.