Read the following passage and mark the letter A, B, C, or D to indicate the best answer to each of the following questions from 18 to 27.

The traditional wisdom "A Jack of all trades, a master of none" has long been held in high regard. However, in today's rapidly evolving world, a new breed of innovators is challenging this maxim. They are the polymaths, multi-talented individuals, also known as Renaissance men, who not only dip their toes into various fields but dive deep and come up with pearls of innovation. They are jacks of all trades, and masters of many. Take, for instance, the audacious genius of Elon Musk.

Born in Pretoria, South Africa, Elon Musk-the man behind PayPal, Tesla, SpaceX, and Neuralink-is the epitome of a modern-day Renaissance man. [I] Each of his ventures operates in entirely different sectors: digital payments, automotive, aerospace, and neurotechnology. [II] He disrupts, revolutionises, and masters each of them. [III] Without formal education in rocket science, he founded SpaceX, the first privately-funded company to send a spacecraft to the International Space Station. Similarly, although he didn't start in the automotive industry, Tesla has become a leader in the electric vehicle market, heralding a new era of sustainable transportation. [IV]

Musk's secret weapon is a concept called 'first principles thinking,' a problem-solving method used by Aristotle and another renowned polymath, Leonardo da Vinci. This approach involves breaking down complex problems into their most fundamental parts and building up solutions from scratch. It enables Musk to venture into unknown territories, question assumptions, and come up with innovative solutions.

Musk's success substantiates the argument that in our complex and rapidly evolving world, being a specialist might limit the ability to innovate across boundaries. In contrast, a well-rounded, multi-disciplinary approach opens up endless avenues of creativity and innovation. Today's entrepreneurial landscape increasingly values generalists, who have a broad view of the world, understand various disciplines, and integrate their knowledge to come up with creative solutions. A jack-of-all-trades approach equips entrepreneurs with diverse skills, allowing them to see the bigger picture and navigate the complexities of the business world.

The word "It" in paragraph 3 refers to __________.