Which of the following is Autotriploid?

Answer: Option A

Cynodon dactylon is Autotriploid.
An autotriploid would have three copies of the basic chromosomal set. One way to produce an autotriploid is by mating a diploid with a haploid (n) gamete and a tetraploid with a 2n gamete. The offspring would have unbalanced gametes and therefore possibly be sterile.
Autotriploids have three chromosome sets derived from a single taxon, and cyanadon has the same.