Explanation:

Mammal with True Placenta:
The correct answer to the question is D, mongoose. This is because a mongoose is a mammal that possesses a true placenta.

Placenta:
- The placenta is an organ that develops in the uterus during pregnancy.
- It allows for the exchange of nutrients, gases, and waste products between the mother and the developing fetus.

Types of Mammals:
- There are three main types of mammals based on their reproduction methods: monotremes, marsupials, and placental mammals.
- Monotremes, like the echidna and platypus, lay eggs and do not have a true placenta.
- Marsupials, like the kangaroo, give birth to relatively undeveloped young that continue to develop in a pouch.
- Placental mammals, like the mongoose, have a true placenta that nourishes the fetus during pregnancy.

Logic Behind the Question:
- The question tests the knowledge of the different reproductive strategies of mammals.
- By knowing the characteristics of each type of mammal, one can determine which group a particular species belongs to based on specific traits like the presence or absence of a true placenta.

In conclusion, the question about mammals with a true placenta is based on understanding the reproductive strategies of different mammal groups. Knowing the unique features of each type of mammal allows one to correctly identify which species possess a true placenta, like the mongoose.