[A]: The evolution of molecular oxygen is con- cerned with photosystem-1 (PS-I).
[R]: The photosystem-11 (PS-II) is not involved in the evolution of oxygen

Options

A. If both A and R are true and R is the correct explanation of A
B. If both A and R are true but R is not the correct explanation of A
C. If A is true and R is false
D. If both A and R are false

Answer

To solve the question regarding the evolution of molecular oxygen and its association with photosystems, we can break it down step by step:

### Step 1: Understand Photosystems
Photosystems are complexes in the thylakoid membranes of chloroplasts that play a crucial role in photosynthesis. There are two main types: Photosystem I (PS-I) and Photosystem II (PS-II).

### Step 2: Identify the Role of PS-II
Photosystem II (PS-II) is primarily responsible for the photolysis of water, a process that splits water molecules into oxygen, protons, and electrons. This reaction occurs when PS-II absorbs light energy, specifically at a wavelength of about 680 nanometers.

### Step 3: Clarify the Role of PS-I
Photosystem I (PS-I) absorbs light at a longer wavelength (around 700 nanometers) and is involved in the reduction of NADP+ to NADPH, but it does not directly contribute to the evolution of molecular oxygen.

### Step 4: Analyze the Statements
- Statement [A]: "The evolution of molecular oxygen is concerned with photosystem-1 (PS-I)" is incorrect because PS-I does not produce oxygen.
- Statement [R]: "The photosystem-11 (PS-II) is not involved in the evolution of oxygen" is also incorrect because PS-II is indeed responsible for the evolution of oxygen.

### Conclusion
Both statements are false. The correct understanding is that PS-II is the photosystem involved in the evolution of molecular oxygen, while PS-I plays a different role in the photosynthetic process.

### Final Answer
Both statements [A] and [R] are false.

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