Which Scenario Would Tend to Make Obtaining Correct Sequence Alignments

Which scenario would tend to make obtaining correct sequence alignments difficult?

A) Comparing closely related species
B) Examining slowly-evolving sequences
C) Working with a segment of DNA in which deletions frequently evolve
D) Knowing which types of substitutions are most likely to evolve
E) Having sequences of a gene from several species at different degrees of evolutionary relatedness from one another