Below is the structure of 3-Methylpentane. The word pentane in name specifies the parent chain which ends on -ane (alkane) and pent- shows number of carbon atoms is parent chain (pent=5). The position of substituent is specified at the start i.e. 3.
B is the correct answer. The exosphere is the outermost region of the atmosphere the gradually merges out into space. The water cycle does not occur within this region.