Can Different Species Have Very Few Visible Morphological Differences or None

Can different species have very few visible morphological differences or none at all?

A) no, because different species must have distinct, visible morphological differences
B) yes, if they are not under selection to evolve such differences (cryptic species)
C) yes, if they are hybrids of other species
D) yes, when their DNA is identical
E) no, because their DNA is not identical, and phenotype must always reflect genotype