Which of the following are functions of trademark? To signify that all goods bearing the trademark are of equal quality level. To distinguish one seller's good from another's. To signify that all goods bearing the trademark or service mark come from a single source. To serve as a primary instrument in buying and selling. To stop people using your goods without your permission.

To signify that all goods bearing the trademark are of equal quality level: Yes, this is one of the functions of a trademark. It assures consumers that all products with this mark meet a certain level of quality.

To distinguish one seller's good from another's: Yes, this is a primary function of a trademark. It helps consumers distinguish between products from different companies.

To signify that all goods bearing the trademark or service mark come from a single source: Yes, this is another key function of a trademark. It indicates that all goods with this mark come from the same producer or manufacturer.

To serve as a primary instrument in buying and selling: Yes, trademarks play a crucial role in commerce by helping consumers identify products they wish to purchase.

To stop people using your goods without your permission: Not exactly. While a trademark does provide some legal protection against unauthorized use, its main purpose is not to prevent people from using the goods, but rather to prevent others from using the same or a confusingly similar mark.