Jake developed a toothpaste using only natural ingredients, and he has been quite successful selling the product in health food stores and some grocery stores. He has recently developed a toothbrush using bamboo and natural components. Jake is considering a $\_\_\_\_\_\_\_\_\_\_,$ giving the toothbrush the same brand name as the toothpaste to have greater brand awareness.

co$-$brand

brand extension

premium brand

natural brand

joint brand