The most accurate comparison between an amoeba and a red blood cell is:
An amoeba is responsible for all functions, and a red blood cell is responsible for some functions.
This is because an amoeba is a single-celled organism that performs all necessary life functions (such as feeding, movement, and reproduction) within one cell. In contrast, a red blood cell is a specialized cell with a specific function (transporting oxygen) and is part of a multicellular organism (human or other animals) that relies on many different types of cells to perform different functions.