Answer:
Different actin-binding proteins
Step-by-step explanation:
Actin is one of the most abundant proteins of the cytoskeletal structure as it forms a highly organized structure of actin called actin bundles and actin network.
The actin form these two different types of actin structures based on the different types of actin-binding proteins.
The binding proteins which help form the actin bundles are inflexible and short proteins like fimbrin form the closely packed structure of actin arranged parallelly.
The binding proteins which help form the actin filaments are flexible and longer like filament which forms the loosely packed structure called actin network.
Thus, Different actin-binding proteins are the correct answer.