Plant tissues where carbon fixation occurs are known as ‘source’. The product(s) formed is/are then transported to different parts of the plant body for its further utilization or storage, which is known as ‘sink’. Which of the following can be categorized as ‘source (P)’and ‘Sink (Q)’? 

(a) (P) endodermis of root; (Q) phloem cells of root 

(b) (P) epidermal region of assimilatory root; (Q) meristematic region ‘of assimilatory root 

(c) (P) parenchyma of beet tuber; (Q) phloem cells of root 

(d) (P) xylem tissue of a green leaf; (Q) phloem tissue of the adjacent green leaf