How is a debt ratio of $0\mathrm{.}45$ interpreted?

Multiple choice question.

A debt ratio of $0\mathrm{.}45$ means that a firm has $$0\mathrm{.}45$ of equity for every dollar of debt.

A debt ratio of $0\mathrm{.}45$ means a firm has $$0\mathrm{.}45$ of current liabilities for every dollar of current assets.

A debt ratio of $0\mathrm{.}45$ means that for every dollar of assets, a firm has $$0\mathrm{.}45$ of debt.

A debt ratio of $0\mathrm{.}45$ means that a firm has $$0\mathrm{.}45$ of debt for every dollar of equity.