Carbon is an organic element which is key to <em>Chemistry</em> and <em>Biochemistry</em>. It usually forms a <em>covalent bond with atoms</em>. It commonly bonds to elements having similar <em>electronegativity</em>. <em>Non-metal elements</em> that typically bond to carbon are <em>oxygen, hydrogen, sulfur and nitrogen</em>. Moreover, carbon can also bond to <em>phosphorus </em>and <em>halogens</em>, as well as <em>metallic elements</em>, such as <em>iron </em>and <em>nickel</em>, with which it forms highly <em>covalent compounds.</em>
A) a common ancestor Homologous structures are structures that are similar in related organisms. There is a basic pattern of bones which can be inherited from a common ancestor