The correct answer is (a).
Gandhiji believed that non-violence is the only way to attain truth. He said that violence is a form of self-destruction and that it can never lead to lasting peace. He believed that non-violence is the only way to achieve true freedom, both for individuals and for nations.
(b) is incorrect because Gandhiji believed that non-violence is not just a way to win political freedom, but also a way to live a moral life. He said that non-violence is the only way to achieve true peace and happiness.
(c) is incorrect because Gandhiji believed that non-violence is not the only way to realize God. He said that there are many paths to God, and that non-violence is just one of them.
(d) is incorrect because Gandhiji believed that non-violence is not an end in itself. He said that non-violence is a means to an end, and that the end is to achieve truth and peace.