The correct answer is D. Samkhya.
Samkhya is the oldest of the six orthodox schools of Hindu philosophy. It is a dualistic system that posits the existence of two fundamental principles: Purusha (consciousness) and Prakriti (matter). Purusha is eternal and unchanging, while Prakriti is constantly changing. The goal of Samkhya is to achieve liberation from the cycle of rebirth by discriminating between Purusha and Prakriti.
Yoga is a system of philosophy and practice that originated in ancient India. It is a holistic system that aims to unite the individual consciousness with the universal consciousness. Yoga is often associated with physical postures, but it also includes breathwork, meditation, and other practices.
Vedanta is a system of Hindu philosophy that is based on the Upanishads. It is a non-dualistic system that posits the existence of one ultimate reality, Brahman. The goal of Vedanta is to realize oneness with Brahman.
Nyaya is a system of Hindu philosophy that is based on the study of logic and reasoning. It is a realist system that posits the existence of an external world. The goal of Nyaya is to achieve liberation from the cycle of rebirth by acquiring knowledge of the true nature of reality.
The six orthodox schools of Hindu philosophy are: Samkhya, Yoga, Vedanta, Nyaya, Vaisheshika, and Mimamsa. These schools were developed over a period of several centuries, and they represent a wide range of philosophical views.