Read the passage carefully and choose the best answer to the question out of the four alternatives.
A knowledge of grammar is essential for good speaking and writing, by which one's mind is judged. Studying grammar means hard work: it must be learned as a whole, with no part omitted, and it demands much thought and patience. But, once acquired, it can give a life-time's pleasure and profit. Its study requires no physical hardship, no special room or expenses. If people spent only their leisure time studying grammar they could master it in one year. The author learned it in less than a year. As a private soldier earning sixpence a day, he sat on his bed and studied. Unable to afford candle or oil, he read in winter by firelight (when it was his turn). If he could manage it thus, and with no outside encouragement, then any youth, however poor or busy, could do the same.