Answer: Option A
Explanation:
ESTs are Expressed sequence tags, which are the segments of mRNA sequences that is derived through the single sequence reactions performed on the clones from cDNA libraries which were randomly selected.
This is possible by the help of bioinformatics that this much of data is available nowadays for study and research purpose.
Till date we have 45 million expressed sequence tags obtained from over 1400 species or can be said as eukaryotic species.