ANSWER
The element carbon combined with the element oxygen to form a compound carbon dioxide
Step-by-step explanation
Given information
The reaction above shows two reactants reacting to form a single products
Firstly, we will need to define the terms element and compound
Element is a substance that cannot be split into two simpler units by an ordinary chemical reaction.
The compound is defined as the combination of two or more elements that are chemically combined together
Therefore, from the given reaction, we can say that oxygen and carbon are elements, and they are reacting to give a product that is a compound (carbon dioxide).
Hence, the element carbon combined with the element oxygen to form a compound carbon dioxide