James MacGregor Burns introduced the concept of 'transformational leadership' in his 1978 book 'Leadership', distinguishing it from 'transactional leadership'. Burns argued that transformational leaders inspire followers to achieve extraordinary outcomes and, in the process, develop their own leadership capacity. The other options listed are not recognized as leadership scholars - Pradip Sindhu is a tech entrepreneur (founder of Juniper Networks), Phillip Kotler is a marketing expert, and Samuel A. DiPiazza was a CEO at PricewaterhouseCoopers.