The correct answer is (B): 4123
4.The criterion of ‘consumer welfare standard’ and the principle that antitrust law should serve consumer interests and that it should protect competition rather than individual competitors was an antitrust law introduced by, and named after, the 'Chicago school'.
1. It advocated a conservative approach to antitrust enforcement that espouses faith in efficient markets and voiced suspicion regarding the merits of judicial intervention to correct anticompetitive practices.
2. Many industries have consistently gained market share, the lion’s share – without any official concern; the most successful technology companies have grown into veritable titans, on the premise that they advance ‘public interest’.
3. That the new anticompetitive risks posed by tech giants like Google, Facebook, and Amazon, necessitate new legal solutions could be attributed to the dearth of enforcement actions against monopolies and the few cases challenging mergers in the USA.
Sentence 4, which discusses the underlying premise of antitrust law while setting the scene, is the finest beginning sentence.
4 and 1 is a sequence, where the first pronoun ('it') in 1 obviously refers to the Chicago school that is named in sentence 4.
Sentence 2 and 3 is an additional connection discusses the steady rise of the tech giants, and sentence 3 points to the lack of enforcement measures as the reason for this.
Therefore, the proper order is 4123.