Match List - I with List - II and choose the correct answer.

List - I		List - II
(a)	S Phase	(i)	Proteins are synthesized
(b)	G2 Phase	(ii)	Inactive Phase
(c)	Quiescent stage	(iii)	Interval between mitosis and initiation of DNA replication
(d)	G1 Phase	(iv)	DNA replication

The correct option is a - (iv) b - (i) c - (ii) d - (iii).

Let us understand the events that take place during each phase of the cell cycle to match List - I with List - II:

(a) S Phase (Synthesis Phase):
During this phase, DNA replication takes place in the nucleus, and the amount of DNA per cell doubles. Therefore, (a) matches with (iv) DNA replication.

(b) G₂ Phase (Gap 2 Phase):
During this phase, proteins required for mitosis are synthesized while cell growth continues. Therefore, (b) matches with (i) Proteins are synthesized.

(c) Quiescent stage (G₀ Phase):
Some cells in the adult animal do not appear to exhibit division. These cells exit the G₁ phase to enter an inactive stage called the quiescent stage (G₀) of the cell cycle. Cells in this stage remain metabolically active but no longer proliferate unless called on to do so depending on the requirement of the organism. Therefore, (c) matches with (ii) Inactive Phase.

(d) G₁ Phase (Gap 1 Phase):
This phase corresponds to the interval between mitosis and the initiation of DNA replication. During the G₁ phase, the cell is metabolically active and continuously grows but does not replicate its DNA. Therefore, (d) matches with (iii) Interval between mitosis and initiation of DNA replication.

Combining all the correct matches:
• a - (iv)
• b - (i)
• c - (ii)
• d - (iii)