Answer:
The correct answer is current liabilities is equal to $4.5 million and firm's level of inventory is $2.25 million.
Explanation:
Both current ratio and quick ratio are know as liquidity ratio which tells about the ability of a firm to meet its short term obligations.
The only difference between these two ratio is of taking inventory and prepaid expenses in to account, as while calculating the quick ratio we don't take inventory and prepaid expenses in to account.
Formula for current ratio = 
Where the current ratio is 2.0 and current assets is equal to $9 million,

CURRENT LIABILITIES = $4.5 MILLION
Formula for quick ratio = 
Here current liabilities = $4.5 million,
Quick asset = current assets - inventory

INVENTORY = $9 MILLION - $6.75 MILLION
INVENTORY = $2.25 MILLION