When hydrogen is replaced by another element in a hydrocarbon, the reaction is called: addition substitution hydrogenation combustion

substitution

Explanation:

Addition reaction is defined as the reaction in which two reactants get added to give single product.

Substitution reaction is defined as the reaction in which one atom replaces the other atom from the compound.

Hydrogenation is addition of hydrogen to unsaturated hydrocarbons.

Combustion is a type of chemical reaction in which fuel is reacted with oxygen to form carbon dioxide and water.

Example:  

not clear

under a microscope, cancer cells may look very different from normal cells. they often have different sizes and some may be larger than normal while others are smaller. cancer cells are often abnormally shaped and the control centre of the cell (the nucleus) may have an abnormal appearance.

i think? ?