If one compares the base sequences of related genes from different species, one is likely to find that corresponding are usually conserved, but the sequences of are much less well conserved.
A. chaperons; exons
B. introns; exons
C. introns; chaperons
D. exons; introns
E. introns; proteins

B. introns; exons

Explanation:

Related genes from different organism usually translate to proteins of indispensable functions. This means that the proteins must be similar in terms of amino acids produced. Therefore the coding region must be highly conserved. These can be found in the introns. Conversely, exons are not a part of the coding sequence and therefore not required for translation. These sequences may be less conserved.