Ini apa jawabnya.....

Kelas: SMA
Pelajaran: English
Kategori: reading comprehension
Pembahasan: 

39. D. (such is based on the personal life of Adam Smith, who could finally finish his doctorate/ PhD)
40. A. (without his persistence in learning, he wouldn't be able to be the expert in Economics after studying mathematics to start with and followed by PhD degree in Philosophy)
41. D (as he managed to write his second incomparable book, An Inquiry to the Nature and Causes of The Wealth of Nations, which practically about economy from the philosophy point of view with complex mathematical calculations)
42. B (the meaning is literal or obvious, though in the economy context, it's unexplained power to create balance in an ideal economic situation, without any tampered effort for own profit or manipulations)