The general pattern is that there will be one primary source and one secondary source to read each week. This week that means Blagdon and Higgonet respectively. The various "options" are available as substitutes for Blagdon, depending on your language preferences and curiosity. There is never any obligation to choose an "optional" reading, but by the same token, you are free to ignore Blagdon and read a primary source in another language. The same pattern holds for future weeks.