The statements that are TRUE:
(A) Methane leads to both global warming and photochemical smog
(B) Methane is generated from paddy fields
(C) Methane is a stronger global warming gas than CO$$_2$$
(D) Methane is a part of reducing smog
Choose the most appropriate answer from the options given below:

Let us evaluate each statement about methane:

(A) Methane is a greenhouse gas that contributes to global warming. It also participates in photochemical reactions in the atmosphere that can contribute to smog formation. So statement (A) is true.

(B) Paddy fields (rice paddies) are a well-known source of methane, produced by anaerobic decomposition of organic matter in waterlogged soil. So statement (B) is true.

(C) Methane is indeed a stronger greenhouse gas than CO$$_2$$ — its global warming potential is about 80 times that of CO$$_2$$ over a 20-year period (or about 25 times over 100 years). So statement (C) is true.

(D) Reducing smog is associated with reducing agents like hydrocarbons in a reducing atmosphere (as opposed to oxidizing/London smog). However, methane is typically classified as contributing to photochemical (oxidizing) smog, not reducing smog. Statement (D) is false.

The true statements are (A), (B), and (C) only.

The answer is $$\boxed{\text{(A), (B), (C) only}}$$.