Selective uptake of ions is ensured at the level of:
Endodermis (C) is correct here. This is core WATER TRANSPORT: once you know the definition or pathway step, Endodermis is the clear fit. The wrong ones are A) Epidermis; B) Cortex; D) Pericycle. If the topic is about gradients or potentials, water/solutes move from higher to lower of the relevant quantity.
Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.