Bioinformatics can be used to scan sequences for probable genes looking for start and stop sites for transcription and for translation, for probable splice sites, and for sequences known to be found in other known genes. such sequences containing these elements are
a) expressed sequence tags.
b) cdna.
c) multigene families.
d) proteomes.
e) short tandem repeats.

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.

the answer to your question is:

c. complementary base-pairing

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