Given:
The number of novels=3
Scoop, light and Lanark.
Condition is given that Keishas can choose to take some or none, but not all, of these novels.
Let,
A denote the novel Scoop.
B denote the novel Light.
C denote the novel Lanark.
1) Keishas dont choose any novel it is given by,
[tex]N=\mleft\lbrace\emptyset\mright\rbrace[/tex]2) Keishas choose 1 novel and it can any one from 3 novels.
[tex]\begin{gathered} N_1=\mleft\lbrace A\mright\rbrace \\ N_2=\mleft\lbrace B\mright\rbrace \\ N_3=\mleft\lbrace C\mright\rbrace \end{gathered}[/tex]3) Keishas choose 2 novel and it can any two from 3 novels.
[tex]\begin{gathered} N_1=\lbrace A,B\rbrace \\ N_2=\lbrace A,C\rbrace \\ N_3=\lbrace C,B\rbrace \end{gathered}[/tex]Hence, the list all the possible sets of novels that Keisha can take is,
[tex]\mleft\lbrace\emptyset,\mleft\lbrace A\mright\rbrace,\mleft\lbrace B\mright\rbrace,\mleft\lbrace C\mright\rbrace,\mleft\lbrace A,B\mright\rbrace,\mleft\lbrace B,C\mright\rbrace,\mleft\lbrace A,C\mright\rbrace\mright\rbrace[/tex]