The people that president-elect Donald Trump has selected to lead federal health agencies in his second administration include a retired congressman, a surgeon and a former talk-show host. All of them could play pivotal roles in fulfilling a new political agenda that could change how the government goes about safeguarding Americans’ health — from health care and medicines to food safety and science research. If Congress approves, prominent environmental lawyer and anti-vaccine organizer Robert F. Kennedy Jr. will helm the team. Here’s a look at the nominees’ potential role in carrying out what Kennedy says is the task to “reorganize” agencies.