Which of the following substances is formed during photosynthesis a.carbon dioxide
b.light
c.sugar
d.water

The answer is C, Sugar.

An array of chemical reactions done by plants to transform energy from the Sun into chemical energy, that is, in the form of sugar is known as photosynthesis. Primarily, the plants utilize sunlight's energy to react water and carbon dioxide to generate glucose (sugar) and oxygen. In plants, the process of photosynthesis takes place in the chloroplasts.  

The answer is the last option. Electronegativity is the measure of the attraction that an atom has for electrons involved in chemical bonds.  It relates to covalent bonds where electrons are shared. The Pauling scale is the most used.