Solution

(A) Sugarcane has kranz anatomy in their leaves: True, sugarcane, a C₄ plant, has kranz anatomy specialized for efficient photosynthesis under high light and temperature. (B) Maize is a C₄ plant: True, maize utilizes the C₄ photosynthetic pathway which is more efficient under high light intensity and temperatures. (C) Photolysis of water requires Mg⁺⁺ ions: False, photolysis of water requires light and involves enzymes associated with manganese, not magnesium. (D) C₄ pathway of photosynthetic CO₂ fixation was discovered by Hatch and Slack: True, this pathway was identified by Hatch and Slack, explaining a more efficient photosynthesis mechanism.