Final answer:
Donquixote Doflamingo ate the String-String Fruit, allowing him to control strings and manipulate others like puppets. Therefore, the correct option is c.
Step-by-step explanation:
The character who ate the String-String Fruit, allowing him to control strings and manipulate others like puppets, is Donquixote Doflamingo in the anime and manga series "One Piece."
Donquixote Doflamingo, also known as Doflamingo or Joker, is a major antagonist in the series. He possesses the Paramecia-type Devil Fruit called the String-String Fruit or Ito Ito no Mi, which grants him the ability to produce and control strong strings.
He can create sharp and durable strings that he uses for various attacks, as well as manipulate others by controlling their movements like puppets.
In the series, Monkey D. Luffy, the protagonist, has a different Devil Fruit power called the Gomu Gomu no Mi, which gives him the ability to stretch his body like rubber. Luffy does not have the ability to control strings or manipulate others.