Selection bias is a systematic error that would occur due to improper randomization of a sample while collecting. This leads to some members of the population to be less likely to be included than others. Only plants from one side of the highway will be tested.
The following is correctly matched with its tissue system is -
4) stele/vascular tissue system
Stele is the the central core/cylinder of the stem and root of a vascular plant, consisting of the xylem and phloem and other supporting tissues. Vascular plants include clubmosses, horsetails, ferns, gymnosperms etc.