What is the primary purpose of root systems in terms of plant support?

The primary purpose of root systems in terms of plant support is to provide anchorage to the plant. Roots help secure the plant in the soil, preventing it from being easily uprooted by wind, water, or other environmental factors. This anchorage is crucial for stability, allowing the plant to grow upright and reach for sunlight. Additionally, a well-developed root system can enhance a plant's ability to access water and nutrients from the soil, further supporting its growth and health.

The other options, while relevant to plant functions, do not directly pertain to the primary role of roots in support. Storing sugars is a function of some roots, particularly those in storage organs like tubers, but it is not their primary role concerning support. Absorbing sunlight and assisting in photosynthesis are functions associated with leaves rather than root systems, as roots are primarily concerned with anchoring and nutrient uptake.