Among the given options, the plain associated with Limestone Topography is option 3, Karst plain.

A karst plain is a type of topography that is formed due to the dissolution of soluble rocks such as limestone or dolomite. Limestone is a sedimentary rock that is composed primarily of calcium carbonate. Over time, the water in the area erodes and dissolves the limestone, creating underground caves, sinkholes, and distinct surface features.

On a karst plain, the dissolution of limestone creates a unique landscape with sinkholes, disappearing streams, and underground drainage systems. The surface may appear flat or gently rolling, but it is marked by these karst features. This type of plain is commonly found in areas with abundant limestone deposits.

The other options mentioned in the question are not associated with limestone topography.

- Bajada plain refers to a sloping surface formed by the coalescence of alluvial fans.

- Alluvial plain is formed by the deposition of sediments brought by rivers or streams.

- Pene plain is a gently sloping plain created by erosion and deposition over a long period of time.

Therefore, the correct answer is option 3, Karst plain, as it is specifically associated with limestone topography.