What notable feature characterized the first Tesco store opened in 1929?

The first Tesco store opened in 1929 is notably characterized by its origins as a market stall. This foundational aspect highlights the company's modest beginnings and distinguishes it from later developments in the supermarket industry. The transition from a market stall to a grocery store marks a significant evolution in retail, showcasing Tesco's growth from a simple trading concept to a prominent grocery chain.

The other options do not accurately reflect the characteristics of Tesco's first store. Although the company would later expand and implement innovative services such as online shopping, these features were not present in its initial store. Similarly, while Tesco would grow to become a major player in the supermarket sector, it was not the largest supermarket of its time at the point of its founding. Additionally, the company's location in London doesn’t uniquely define its initial store compared to the pivotal move from a stall format to a more structured retail format.