Using a search engine, research operating system timelines

Using a search engine, research operating system timelines
then, based on the OS timelines that you find, answer the following questions: 

Question 1. Why do you think Linux and UNIX share more commands than Windows XP and UNIX?

Solution: Windows operating system is built for a different market peoples.It was mainly fancied over using of the GUI rather than the command line.But whereas Linux built after Unix so they have more number of commands in common.

Question 2. Which line of operating systems has recently become more similar to UNIX?

Solution: The line of operating system which has become more similar to Unix is the Mac OS.

Question 3. Which line of operating systems split into two lines, only to merge again later? 

Solution: The line of operating systems split into two lines, only to merge again later is like MS-Dos in command line and later it is merged into Windows.

Question 4. Why do you think most versions of Linux and Windows use the cd command to change directories? 

Solution: The command is very easy to understand as cd refers to change directory which gives a specific meaning.And also the command is taken from the Unix system