Which of the following is acyclic?
What do you mean by cyclic and acyclic compounds?
→ Cyclic compounds are compounds in which one or more series of atoms in the compounds is connected to form a ring.
→ Here, you can say that the compounds which do not form a ring are acyclic compounds.
Now, as you can see options (a) and (b) do not form rings. Therefore, they are acyclic compounds.