In TypeScript, if you encounter the error "element implicitly has an 'any' type because index expression is not of type 'number'", what is the likely cause?
A) Using a string to index an array, which requires a numeric index.
B) Declaring a variable without specifying its type.
C) Using a number to index an object, which expects a string key.
D) Attempting to call a method that does not exist on the object.