All of the following proteins are part of the thin filaments except

Titin protein.

Explanation:

Titin proteins are present in vertebrate striated muscle, and they are playing important role in contraction of striated muscle. It is the largest known protein in humans, after actin and myosin. It is the most abundant protein in muscles and they encoded with the help of TTN gene in humans.

Thin filaments mainly contains three different types of proteins which are known as:

1) Actin.

2) Tropomyosin.

3) Troponin.

answer; i believe that the correct answer is (lung);

"a.) well–developed vascular system."