The correct option is B Stoic
'A person who is indifferent to both pleasure and pain' is Option C, Stoic. Option A, 'Saint' is a holy person. Option B, 'Ascetic' is a person who leads simple life, avoiding physical pleasures, especially for religious reasons.. Option D, 'Hermit' is a person who lives alone, apart from the society, especially for religious reasons. Thus, options A, B and D are incorrect and the correct word for the given phrase is Option C, 'Stoic'.