Which description best defines a systemic herbicide?

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Systemic herbicides are absorbed by the plant and then transported within its vascular system to reach growth tissues. After entering through leaves or roots, the chemical moves via the xylem and/or phloem to meristematic regions where growth occurs, causing inhibition or death of the whole plant. This internal movement is what lets the herbicide affect parts of the plant that weren’t directly sprayed, unlike contact herbicides that kill only the tissue they touch and don’t move inside. Soil-acting products, on the other hand, stay in the soil and may affect subsequent vegetation rather than moving through the plant itself. So, the description that it enters the weed and moves within the weed to prevent growth captures the defining feature of systemic herbicides.