Define RCB's
Kindly refer to the link provided below:
https://www.meritnation.com/ask-answer/question/what-are-rbc-cells-and-what-it-its-functions/biology/6573641
https://www.meritnation.com/ask-answer/question/what-are-rbc-cells-and-what-it-its-functions/biology/6573641