Which of the following is the formula for calculating the liquidity ratio?

• a$\frac{\text{Current liabilities} - (\text{Inventory} + \text{Prepaid expenses})}{\text{Current liabilities}}$
• b$\frac{\text{Current asset} + (\text{Inventory} - \text{Prepaid expenses})}{\text{Current asset}}$
• c$\frac{\text{Current asset}}{\text{Current liabilities}}$
• d$\frac{\text{Current asset} - (\text{Inventory} + \text{Prepaid expenses})}{\text{Current liabilities}}$