Final answer:
The owner's equity in the company is $250,000.
Step-by-step explanation:
In a company balance sheet, owner's equity is calculated by subtracting the total liabilities from the total assets.
In this case, the total assets are given as $400,000 and the liabilities are $150,000. To find the owner's equity, we subtract the liabilities from the total assets: $400,000 - $150,000 = $250,000.
Therefore, the owner's equity is $250,000, which corresponds to option a).