Utilize the input text as a context reference, choose the right relationship between Frozen and single from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

For the fourth quarter, total Conagra Frozen retail sales grew 26.2% over last year with strong growth across each Frozen category, including single serve meals, vegetables, multi-serve meals, and plant-based meat alternatives.

Answer: distribution_format