The provided context highlights that the main thought or idea (मुख्य विचार) conveyed through the character Uma and her perspective on education is having self-strength and independent thoughts. Option (घ) in the textbook questions explicitly states that the true meaning of education in Uma's view is 'आत्मबल और स्वतंत्र विचार रखना', which forms the central theme of the play 'रीढ़ की हड्डी'.