Final answer:
The main theme is heard and developed throughout the entire first movement of Beethoven's Fifth Symphony, recurring in the exposition, development, and recapitulation.
Step-by-step explanation:
The component that is heard and developed throughout the entire first movement of Beethoven's Fifth Symphony is the main theme. This theme is recognizable by its famous four-note motif, often described as 'short-short-short-long,' and it recurs in various forms throughout the movement.
Beethoven intricately weaves this theme through the exposition, where it is presented, the development section, where it is elaborated and transformed, and during the recapitulation, where it returns in its original form to provide a sense of cohesion and unity to the movement.