Answer:Through energy from the Sun
Explanation: The kingdom Protista contains one of the most difficult set of organisms to classify. This is may be because it includes organisms that resemble early plants such as *Algae,Animals such as Protozoa and fungi mildews.The Protista belong to the group of organisms that do not fit neatly into Plant,Animal and Fungi kingdoms.
The Algae have a distinct chlorophyll and are Autotrophic in their nutrition.Their photosynthetic pigments include Chlorophyll, Carotenoids and Phycobilins.
Algae(a Protista) photosynthesize by capturing a small fraction of energy from the Sun and store it in the chemical bonds of substances. The photosynthetic process in Algae occurs in various coloured antannae pigments called *chromoplast*.
These organisms which *get their energy from the sun*,do so using organelles in their cells called chloroplast ( chromoplast in Algae). The cells absorb sun's radiant energy and use it to drive electrons from water to carbon dioxide and thus form *energy-rich products such as starch and sucrose*.
The three principal Raw materials for photosynthesis are *water,carbon dioxide and light*.