What type of chemical reaction occurs when the body breaks down fats and sugars that supply it with energy? A. electrical
B. Exothermic
C. Physical
D. Endothermic

c- cold periods in earth's history during which glaciers covered much of the surface.

explanation:

c is having 4 valence electrons and is bonded to three hydrogens and one sulphur atom, therefore, the number of bond pair is equal to four. as all the valence electrons are used in forming the bonds so, there is no lone pair left on carbon.

s is having 6 valence electrons and is bonded to one other sulfur atom and one carbon atom, therefore, the number of bond pair is equal to 2. as only two valence electrons are used in forming the bonds so, four electrons are left. therefore, two lone pairs are present on s.