Answer:
Only A and B are redox
Explanation:
Redox reactions are ones where elements change their oxidation states. That means any reactions that involve free elements that are also in compounds, ex: Na in a) is in both 2Na and 2NaCl are redox because their oxidation states change from 0 to whatever in the compound. This means A and B are redox reactions.
For C, (CO3) has a charge of -2, and reactants have charges C = +4, O = -2, and H = +1
The product compounds are all zero charge, so charges C = +4 and O = -2 makes CO2 charge 0 and H = +1 and O = -2 also gives H2O a zero charge. Since al elements of reactants are products do not have a change in charge, it is not redox.
Note that Oxygen is almost always at a charge of -2, that should help you with calculations.
Similarly in d), (NO3) has charge -1, with charge N = +5, O = -2, and Pb = +2.
K tends to have charge +1 and I -1.
For d) reactants, Pb = +2 and I = -1 still gives PbI2 a zero charge. KNO3 also leaves it a zero charge.
Therefore d) also does not have any charge change in elements so it is not redox
