| A. Human beings are free when they are alone and can think for themselves | B. Human beings are free even though all their decisions are causally determined | ||
| C. The human being as experienced and thought about by others is subject to causality | D. The mind of the human being is free but the body can be quite expensive | ||
Kant thinks there are two aspects to a thing: how they appear when they are being perceive, thought about, etc., and how they are 'in themselves'. He thinks that the self as it is in itself (the 'noumenal self') is free, but the self as it appears belongs to the world of appearance (the 'phenomenal self') is subject to causality just like everything else in the phenomenal world.
So (C) is the best answer.
(A) is not quite right because even when you are alone the aspect you think about is your phenomenal self (it is this aspect that has desires and feelings).
(B) seems wrong because Kant thinks our decisions are not causally determined.
(D). is whimsical.
(I don't myself have an answer to the question: how can a decision freely made by the noumenal self have an impact o n the phenomenal world, which is under the rigid determinism of the causal principle?)