Final answer:
TCBY is using a product development strategy by adding a new flavor to its menu, aiming to increase its market share within its existing customer base.
Step-by-step explanation:
When TCBY, the frozen yogurt chain, decides to add a new flavor to its menu, product development is the brand strategy being utilized. This strategy involves introducing new products or enhancements to existing products within the current market that the company already serves. By doing so, TCBY aims to attract more customers or to encourage existing customers to purchase more, effectively increasing their market share without venturing into new markets or customer segments.