Which of the following is NOT a benefit of greenhouses?

Greenhouses are designed to create optimal growing conditions for plants. The primary benefits include protecting plants from pests, controlling temperature and humidity levels, and providing access to natural sunlight.

When considering the role of greenhouses, increasing soil pH is not a direct advantage. In fact, the pH of soil is influenced by various factors including the type of soil, the materials added to it, and the plant species being grown rather than being a specific benefit of the greenhouse environment itself. Soil pH can be adjusted through amendments but this process is independent of greenhouse structures. Therefore, the correct choice highlights that increased soil pH is not a benefit provided specifically by the greenhouse setting.