1. Examine the following list of permissions for four items included in a directory listing. Identify if it is a file, directory, or other. Specify the access allowed to three categories: world, user, and group. Identify any category of users who are denied any access to all of these files.

a. -rwx- - -r-x
b. drwx- - -rwx
c. d- -x- - -r-x
d. prwx- - - - - - -

2. Linux uses an LRU algorithm to manage memory. Suppose there is another page replacement algorithm called not frequently used (NFU) that gives each page its own counter that is incremented with each clock cycle. In this way, each counter tracks the frequency of page use, and the page with the lowest counter is swapped out when paging is necessary. In your opinion, how do these two algorithms (LRU and NFU) compare? Explain which one would work best under normal use, and define how you perceive "normal use".

1. Compare and contrast Android and the Linux operating systems.

2. Compare and contrast the Android and Windows operating systems.

3. The role of the Linux kernel is crucial to the Android operating system. Explain in your own words why this is so.