What is $Chlamydomonas$?

Algae include unicellular forms like $A$,filamentous forms like $B$,and colonial forms like $C$. Here $A, B$,and $C$ refer to:

Which of the following algae has a filamentous structure?

Reproduction in $Spirogyra$ is

Storage bodies,pyrenoids in the chloroplast contain

An example of a colonial alga is