Which of the following conditions is a characteristic of a poorly drained soil?

This question is asking about a characteristic of a poorly drained soil. A poorly drained soil is a type of soil that does not allow water to drain away easily. It means that water tends to accumulate and stay in the soil for a longer time.

Let's look at the options to find the characteristic of a poorly drained soil.

Option A states that the presence of a large number of termites is a characteristic of a poorly drained soil. However, termites are not directly related to soil drainage. Termites are insects that live in the soil and feed on dead plant material. So, this option is not correct in relation to the question.

Option B mentions the presence of a high amount of humus as a characteristic of a poorly drained soil. Humus is the decomposed organic matter in the soil. While poorly drained soils can have a high amount of humus due to the slow decomposition of organic matter in waterlogged conditions, this is not a specific characteristic of poorly drained soil. So, this option is not correct.

Option C states that there is a decrease in the activities of microorganisms in a poorly drained soil, and this is the correct answer. Poorly drained soils have limited oxygen availability due to the waterlogged conditions. This lack of oxygen negatively affects the activities of aerobic microorganisms, which require oxygen for their survival and functioning. So, this option is the correct answer.

Option D suggests that a poorly drained soil has high soil fertility and productivity. However, poorly drained soils generally have low fertility and productivity because excessive water can cause leaching of nutrients, and waterlogged conditions can lead to root suffocation and poor plant growth. So, this option is not correct.

In summary, the characteristic of a poorly drained soil is a decrease in the activities of microorganisms. This is because the waterlogged conditions limit the amount of oxygen available in the soil, which affects the functioning of aerobic microorganisms.