An open-circuited p-n junction has drift current flowing from the n-side to the p-side. The option A is true.

An open-circuited p-n junction has diffusion current flowing from the p-side to the n-side. The option B is false.

The drift current flowing from the n-side to the p-side if the junction is forward-biased, is true but the drift current flowing from the p-side to the n-side if the junction is reverse-biased, is false. Hence, the option C overall is false.

The drift current flowing from the p-side to the n-side if the junction is forward biased is false but the drift current flowing from the n-side to the p-side if the junction is reverse-biased, is true. Hence the option D overall is false.

Therefore, the correct answer is Option A.