Neoteny refers to
A. Development of gonads
B. Moulting
C. Metamorphosis
D. Retention of larval traits in the adult body

Hint: Neoteny is referred to slowing of the physiological development of an organism. The word juvenilization also refers to the word neoteny and typically refers to an animal. The word progenesis refers to accelerated sexual development in an organism.

Complete answer:
Neoteny is the phenomenon in which the juvenile traits are retained in an adult body. The juvenile traits are present both in the early life as well as in the adult of the body. In this there is slow or delayed physical development of an organism which leads to occurrence of such traits in an organism. The larval stage is extended in an organism which results in showing of juvenile characters or traits in an organism.
Moulting is a phenomenon in which shedding, ecdysis and sloughing occurs in which an animal routinely casts off a part of its body at a specific time of year or under certain conditions. Metamorphosis is a process in which transformation of an adult from an immature occurs in two or more distinct stages. The development of the gonads is a process of prenatal development of the reproductive system which leads to formation of testes in males and ovaries in females.

Hence, the correct option is D. Retention of larval traits in the adult body.

Note: Neoteny and progenesis both results in paedomorphism which is a type heterochrony. Paedomorphism is also defined as retention of larval traits which are seen in some organisms like salamanders. Both neoteny and progenesis cause the retention of traits in adults.