The answer is burning coal! Please forgive me if I get this answer wrong!
Answer:
The Eukarya differ from the Archea and Bacteria in that their cells are eukaryotic, meaning they contain a membrane enclosed nucleus and other membrane enclosed organelles.
Explanation:
A single molecule is the one that is responsible for initiating a signal transduction pathway. The answer in this question is a single molecule. Molecule is defined as an electrically neutral group of two atoms or more held together by a chemical bonds.
A. Nutrients, vitamins would also be a correct answer
