Both (A) and (R) are true and (R) is the correct explanation of (A). Unlike animals where $\beta$-oxidation occurs in both mitochondria and peroxisomes, in plants $\beta$-oxidation is exclusively confined to peroxisomes/glyoxysomes. The initial step is catalyzed by fatty acyl-CoA oxidase, which transfers electrons directly to molecular O2, forming hydrogen peroxide ($H_2O_2$). Under abiotic stress, accelerated lipid breakdown triggers massive ROS generation via acyl-CoA oxidase; hence suppressing this peroxisomal step alleviates oxidative burst and enhances stress tolerance.

Both (A) and (R) are true and (R) is the correct explanation of (A). Standard endo- and exo-proteases synthesized by host organisms (e.g., pepsin, trypsin, chymotrypsin) have evolved stereospecific active sites that exclusively recognize and cleave peptide bonds involving L-amino acids. The cross-linked stem peptides in bacterial peptidoglycan uniquely contain D-amino acids (such as D-alanine and D-glutamate), rendering the bacterial cell wall impervious to hydrolytic breakdown by typical proteases.

Roots of leguminous plants such as Derris, Lonchocarpus, and Tephrosia contain high concentrations of the natural botanical isoflavonoid rotenone. Rotenone is rapidly absorbed through fish gills and acts as a potent, specific inhibitor of Complex I (NADH:ubiquinone oxidoreductase) in the mitochondrial electron transport chain. By arresting electron flow from Fe-S centers to ubiquinone, it halts ATP synthesis, rapidly paralyzing fish and forcing them to float to the surface.

• Amytal (barbiturate): Specific inhibitor of Complex I (NADH-Q oxidoreductase); blocks electron flow between Fe-S clusters and ubiquinone, specifically inhibiting $\text{NAD}^+$-linked substrate oxidation without affecting Complex II -> (A) - (II).
• Antimycin A: Specific inhibitor of Complex III (cytochrome $bc_1$ complex) at the $Q_i$ site; it blocks downstream flow from reduced ubiquinone ($QH_2$), thereby inhibiting FAD-linked substrate (succinate) oxidation as well -> (B) - (I).
• TMPD: An artificial redox mediator that donates electrons directly to oxidized Cytochrome c (bypassing Complexes I, II, and III) -> (C) - (IV).
• Sodium azide ($\text{NaN}_3$): Binds to the heme iron of Cytochrome c oxidase (Complex IV), irreversibly halting the terminal step of cellular respiration and completely stopping the oxidation of all electron donors -> (D) - (III).
• Correct matching: (A) - (II), (B) - (I), (C) - (IV), (D) - (III) (Option 3).