Final answer:
With the information provided, it is not possible to accurately determine the values of ps and xt or to choose between the answer options A, B, C, or D due to the lack of necessary context and clear relation to the reference solution.
Step-by-step explanation:
To find the values of ps and xt, we must extract relevant information from the question and the reference solution provided. Unfortunately, the information available in the reference solution does not directly offer the values for ps or xt. This could imply that there are typos in the question or that the question is context-dependent and requires additional information not provided. Given this, we cannot confidently determine the correct answer from the options A, B, C, and D.