$\color{magenta}\text{1D Array}:$ $a[i] \Rightarrow \ * \ (a+i)$
$\color{DarkOrange}\text{2D Array} :$ $a[i][j] \Rightarrow \ *( \ * \ (a \ + \ i) + j)$
$\color{green}\text{3D Array} :$ $a[i][j][k] \Rightarrow \ *( \ *( \ * \ (a \ + \ i ) + j) + k )$
$\color{cyan}\text{4D Array} :$ $a[i][j][k][l] \Rightarrow \ * ( \ *( \ *( \ * \ (a \ + \ i ) + j) + k ) + l) $
$\color{red}\textbf{Ans:}$ $b) \ a[i][j][k][2] \Rightarrow \ * ( \ *( \ *( \ * \ (a \ + \ i ) + j) + k ) + 2) $