Which of the following methods can be used to reduce water intrusion in basements?

Installing proper drainage systems is a highly effective method for reducing water intrusion in basements. Proper drainage systems involve the use of materials and structures designed to direct water away from the foundation of the building. This can include elements like French drains, sump pumps, and gutter systems that collect and channel roof runoff away from the base of the house. When installed correctly, these systems help manage groundwater and surface water, thus minimizing the risk of water seeping into the basement.

By ensuring that water is diverted away from the foundation, these drainage systems play a crucial role in preventing water accumulation around the basement walls and floors, which can lead to significant moisture problems, mold growth, and structural damage over time.

In contrast, relying solely on exterior paint on walls may provide some level of water resistance but does not address the underlying issues of water management or drainage. Maintaining a landscaping slope toward the house contradicts the goal of preventing water from pooling around the foundation, and leaving basement windows open for ventilation can actually allow moisture to enter from outside, particularly in rainy conditions, which could exacerbate water intrusion issues.