The answer is tunicates. Tunicates are commonly known as sea squirts and are in the Chordata phylum, even though they don't have a back bone. Which is really weird. But they just got put into the same category as humans. This is because they have a notocord and a back bone when they are larvae. But they lose all these when they become adults.
Awnser : C Lacks genetic variation
Explanation : The major disadvantages of asexual reproduction are: Lack of diversity. Since the offsprings are genetically identical to the parent they are more susceptible to the same diseases and nutrient deficiencies as the parent. All the negative mutations persist for generations.