问题如下：
An analyst observes the following data for two companies:
Which of the following choices best describes reasonable conclusions that the analyst might make about the two companies’ ability to pay their current and long-term obligations?
选项：
A. Company A’s current ratio of 4.0 indicates it is more liquid than Company B, whose current ratio is only 1.2, but Company B is more solvent, as indicated by its lower debt-to-equity ratio.
B. Company A’s current ratio of 0.25 indicates it is less liquid than Company B, whose current ratio is 0.83, and Company A is also less solvent, as indicated by a debt-to-equity ratio of 200 percent compared with Company B’s debt-to-equity ratio of only 30 percent.
C. Company A’s current ratio of 4.0 indicates it is more liquid than Company B, whose current ratio is only 1.2, and Company A is also more solvent, as indicated by a debt-to-equity ratio of 200 percent compared with Company B’s debt-to-equity ratio of only 30 percent.
解释：
A is correct.
Company A’s current ratio of 4.0 (= $40,000/$10,000) indicates it is more liquid than Company B, whose current ratio is only 1.2 (= $60,000/$50,000). Company B is more solvent, as indicated by its lower debt-to-equity ratio of 30 percent (= $150,000/$500,000) compared with Company A’s debt-to-equity ratio of 200 percent (= $60,000/$30,000).
解析：A公司current ratio=40000/10000=4，D/E=60000/30000=2，B公司current ratio=60000/50000=1.2，D/E=150000/500000=0.3。从比率能看出A公司流动性更好，B公司长期偿债能力更好。A选项正确。B选项current ratio没算对。C选项关于solvent的结论不对。
请问为什么要用debt to equity ratio？