What environmental condition is least favorable for bacterial growth?

Heat and dryness create an environment that is least favorable for bacterial growth due to the lack of moisture, which is essential for bacteria to thrive. While bacteria can survive in various conditions, they typically require warmth and moisture to grow and multiply effectively. High temperatures alone can be detrimental to many bacterial species, especially if combined with dry conditions that inhibit their metabolic processes.

Moisture is a critical factor, as bacteria absorb water to carry out cellular functions. When the environment lacks moisture, even warm conditions may not support bacterial proliferation. Therefore, the combination of heat and dryness limits the ability of bacteria to grow, making it the least conducive environment when compared to the other options, which all include moisture along with various light or temperature conditions that are generally more favorable for bacterial growth.