Option 1 -> Excludes (B) which is essential as labor services are sold at wage rates in capitalism.
Option 2 -> Excludes (C) which is fundamental - capitalist production is for market exchange.
Option 3 -> Includes (A) which uses vague terminology "their own price" instead of the precise "wage rate".
Option 4 -> Correctly includes (B) wage-based labor, (C) production for selling, and (D) government intervention in modern capitalism.
Hence, Option 4: (B), (C) and (D) only -> In a capitalist economy: (B) Labor is treated as a commodity sold at market-determined wage rates; (C) Production occurs primarily for profit through market sales rather than direct consumption; (D) Modern capitalist economies typically involve government intervention to address market failures and ensure equitable distribution. Option (A) is excluded because "at their own price" is imprecise - the correct term is "wage rate" as specified in (B). -> correct