If a corporation wants to raise funds without affecting the level of ownership that each shareholder currently enjoys, the best option from the provided list would be selling bonds.
When a corporation issues bonds, it is borrowing money from investors with the promise to pay back that amount plus interest over time. This does not dilute ownership since no new shares are being issued.
In contrast, buying stocks does not raise funds, issuing stocks would dilute ownership, and selling shareholder assets could affect both ownership stakes and control depending on how assets are distributed or sold.