Question

the colony pointed by arrow \a\ is considered: regular punctiform circular irregular

Explanation:

Punctiform colonies are tiny, pinpoint - sized. In microbiology, when observing bacterial colonies on an agar plate, the description of colony morphology is important. A punctiform colony is characterized by its very small size. Looking at the arrow "A", the colony it points to is of a very small size which fits the description of a punctiform colony. Regular and circular are more about the shape (e.g., a circular colony has a round shape, a regular colony has a uniform and expected shape). Irregular is about a non - uniform or asymmetrical shape. But the key here is the size which is indicative of punctiform.

Answer:

Punctiform