With no explanation, label text_A→text_B with either "DON'T KNOW", "NO" or "YES".
text_A: Vegetable garden bed construction materials should be chosen carefully. Some concerns exist regarding the use of pressure-treated timber. Pine that was treated using chromated copper arsenate or CCA, a toxic chemical mix for preserving timber that may leach chemicals into the soil which in turn can be drawn up into the plants, is a concern for vegetable growers, where part or all of the plant is eaten. If using timber to raise the garden bed, ensure that it is either an untreated hardwood, or one that has been pressure treated without the use of CAA to prevent the risk of chemicals leaching into the soil. A common approach is to use timber sleepers joined with steel rods to hold them together. Another approach is to use concrete blocks, although less aesthetically pleasing, they are inexpensive to source and easy to use.
text_B: Would a backyard vegetable farmer need to find a way to prevent termites from entering the wood at ground level, since no completely-safe forms of treated lumber would be available to them?
NO.