Jainas-
Jainism is an ancient Indian religion that emphasizes non-violence, truth, and the belief in the existence of a soul. Jainas do not believe in destiny determining everything and man being powerless. Instead, they believe in the concept of karma, where one's actions determine their destiny. According to Jainism, individuals have the power to shape their own destiny through their actions and choices.

Buddhists-
Buddhism, founded by Gautama Buddha, also rejects the idea that destiny determines everything and man is powerless. Buddhists believe in the concept of dependent origination, which states that everything arises due to causes and conditions. According to Buddhism, individuals have the ability to break free from the cycle of suffering and attain enlightenment through their own efforts and practice.

Ajivakas-
Ajivakas were a sect in ancient India that believed in the doctrine of fatalism. They believed that destiny determines everything and that human beings have no control over their actions or their future. According to Ajivakas, everything is predestined and humans are merely passive observers of their own lives.

Mimansakas-
The Mimansaka school of philosophy, also known as Purva Mimansa, is a Hindu school of thought that focuses on the interpretation of the Vedas. Mimansakas do not believe in destiny determining everything and man being powerless. They emphasize the importance of rituals and actions prescribed in the Vedas for attaining desirable outcomes. According to Mimansakas, individuals have the power to influence their destiny through their actions and adherence to religious rituals.

Therefore, among the options given, the correct answer is Ajivakas, as they believed in the concept of destiny determining everything and man being powerless.