Step 1: Match each operating system to its corresponding company.
Windows → Developed by Microsoft \(\Rightarrow\) a-iii
Linux → Open Source operating system \(\Rightarrow\) b-i
OSX → Developed by Apple \(\Rightarrow\) c-ii
Android → Owned and developed by Google \(\Rightarrow\) d-iv
Step 2: Confirm the matching.
So, the correct pairing is:
\[
a \to iii,\quad b \to i,\quad c \to ii,\quad d \to iv
\]