What is the macromolecules that builds both cilia and flagella? ?

Microtubules are macromolecules that build both, cilia and flagella.

Microtubules are cytoskeletal fibres that are formed by polymerization of α,β-tubulin and they are important components of cilia, flagella and some other cellular structures. Cilia and flagella are very similar in their organization, both have a central bundle of microtubules-axoneme. Axoneme is compound of nine outer doublet microtubules which surround a central pair of singlet microtubules. Even thought cilia and flagella are structurally similar, they are differentiated based on their function and/or length. Flagella are longer and the primary role of the flagella is locomotion. On the other hand, shorten cilia often has the function in sensing the extracellular environment.

they deliver oxygen to the blood

the real answer is b. scintillation counter