The work of mathematician Roger Penrose in the early 1970s, on the geometry of what are called aperiodic tiles, turned out to describe the architecture of a previously unknown class of crystals.
(A) what are called aperiodic tiles, turned out to describe
(B) what is called aperiodic tiles, describes
(C) aperiodic tiles, describing
(D) so-called aperiodic tiles, describe
(E) aperiodic tiles, it turned out to describe
A is correct
if "what" is used it has to follow with are as what refers to tiles
"describe" refers to "The Work" so it has to be "describes", unless used as an infinitive "to describe"
Only A satisfies the aforementioned statements!