Match the industrial products mentioned in Group I with their producer organisms in Group II.
| Group I | Group II |
| P. Citric acid | 1. Trichoderma viride |
| Q. Cellulase | 2. Clostridium acetobutylicum |
| R. Vitamin B12 | 3. Aspergillus niger |
| S. Butanol | 4. Propionibacterium freudenreichii |
A. P-4, Q-3, R-1, S-2
B. P-3, Q-1, R-2, S-4
C. P-2, Q-1, R-4, S-3
D. P-3, Q-1, R-4, S-2
Answer: Option D

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