Question: The animated character who later used the slogan "The one and only cereal that comes in the shape of animals" to promote Crispy Critters was originally created to promote which cereal?

Context paragraphs:
Ice Cream Cones (cereal): Ice Cream Cones was a breakfast cereal from General Mills that was created in 1987.  The cereal consisted of puffs sweetened for chocolate, vanilla or chocolate chip ice cream flavor, as well as sugar cone-shaped pieces sweetened for sugar cone flavor.  The cereal’s spokesperson was an animated character called Ice Cream Jones, who delivered the cereal on an old-fashioned pedal bike.

Model sheet: In animation, a model sheet, also known as a character board, character sheet, character study or simply a study, is a document used to help standardize the appearance, poses, and gestures of an animated character.  Model sheets are required when large numbers of artists are involved in the production of an animated film to help maintain continuity in characters from scene to scene, as one animator may only do one shot out of the several hundred that are required to complete an animated feature film.  A character not drawn according to the production's standardized model is referred to as off-model.

Miss Caribbean UK: Miss Caribbean UK is an Afro-Caribbean beauty pageant held in the United Kingdom.  It was created by Clayton Brown and Jacqui Brown in 2014.  The stated aims of the pageant are to promote, educate, inspire and celebrate the historical and cultural impact of the Caribbean within the United Kingdom.  The organisation has adopted the slogan "Positively Promoting the Caribbean"™ aiming to inspire, inform and unite all the different Caribbean countries under one umbrella.  The event uses a pageant to promote, educate, inspire and celebrate the historical and cultural impact of the Caribbean within the United Kingdom.  By getting this message to our communities in the UK, we hope realise our objective, which is to, Positively promote the Caribbean.

International Organization of Legal Metrology: The International Organization of Legal Metrology (French: "Organisation Internationale de Métrologie Légale" - OIML), is an intergovernmental organization, created in 1955 and based in Paris, to promote the global harmonization of the legal metrology procedures that underpin and facilitate international trade.  Such harmonisation ensures that certification of measuring devices in one country is compatible with certification in another, thereby facilitating trade in the measuring devices and in products that rely on the measuring devices.  Such products include weighing devices, taxi meters, speedometers, agricultural measuring devices such as cereal moisture meters, health related devices such as exhaust measurements and alcohol content of drinks.

Linus the Lionhearted: Linus the Lionhearted is an American animated television series featuring a main character of the same name.  The character was created in 1959, by the Ed Graham advertising agency, originally as a series of ads for General Foods' Post Cereals.  At first, Linus was the spokesman for the short-lived Post cereal "Heart of Oats" (a Cheerios imitation).  Eventually, the lion was redesigned and reintroduced in 1963, to sell Crispy Critters, which featured Linus on the box.  The ads were so popular that a television series was created in 1964 (with General Foods as sponsor), and ran on the CBS network until 1966, then reruns [in color] aired on ABC from 1966, until it was cancelled three years later.  A coloring book was published which detailed the adventures of So-Hi going on a scavenger hunt in order to break a curse on a two-headed bird, who is then transformed into a boy due to So-Hi's dedication.

Chucklewood Critters: Chucklewood Critters is an American line of television specials and an animated television series created by former Hanna-Barbera animators, Bill Hutten and Tony Love, which centered on two North American woodland animals: Buttons, a young bear cub, and Rusty, a young fox pup.  It started as a Christmas special in 1983 called " The Christmas Tree Train", followed by eight more holiday/seasonal specials.  In 1997 it was developed into a series entitled "The New Chucklewood Critters", which ran for two seasons.

Character animation: Character animation is a specialized area of the animation process, which involves bringing animated character s to life.  The role of a Character Animator is analogous to that of a film or stage actor, and character animators are often said to be "actors with a pencil" (or a mouse).  Character animators breathe life in their characters, creating the illusion of thought, emotion and personality.  Character animation is often distinguished from creature animation, which involves bringing photo-realistic animals and creatures to life.

Duracell Bunny: The Duracell Bunny is an anthropomorphic pink rabbit powered by batteries, used to promote Duracell brand batteries.  Advertisements are based on the concept that the bunny powered by a Duracell alkaline battery can continue functioning longer than an identical device running on inherently lower-duration zinc-carbon batteries.  The advertisements usually feature the bunnies competing in some way, for example, in a game of football, a drumming competition or a race.  In advertisements, the Duracell Bunny is either a standard battery-powered toy, a stop-motion puppet, or a CGI animated character.

Crispy Critters: Crispy Critters was a breakfast cereal manufactured by Post Cereal starting in 1963.  The sweetened cereal, made of oats, consisted of animal-shaped pieces akin to animal crackers. Television commercials featured a cartoon lion, Linus the Lionhearted, voiced by Sheldon Leonard, with the slogan "The one and only cereal that comes in the shape of animals," sung to the tune of "Trepak" from Tchaikovsky's "The Nutcracker" ballet.  The next year, Linus was spun off into a Saturday-morning cartoon show, which ran for two years on the CBS network, then reran on the ABC network for three more until 1969.  After a decline in popularity, the cereal was discontinued.

100% Bran: 100% Bran is a double milled wheat bran breakfast cereal originally manufactured by Nabisco.  It was made by Kraft's Post brand from 1993, when Philip Morris (the owner of Kraft) acquired all Nabisco cereal products, until 2008.  The Post brands were acquired from Kraft by Ralcorp Holdings, Inc., in a sale completed August 4, 2008.  The cereal is a mixture of wheat bran formed into the shape of small sticks and oven toasted.  One serving of this cereal is one-third of a US cup (237 milliliters).  Its sugar content is about 26% in weight

Supporting paragraphs: Crispy Critters Linus the Lionhearted
Answer: Heart of Oats