Solution

While simplifying a CFG, the safest order is:

First remove $\epsilon$-productions.

Then remove unit productions.

Finally remove useless symbols and productions.

Reason:

After removing $\epsilon$-productions, new unit productions may be created.

After removing unit productions, some symbols may become useless.

So, useless symbols should be removed at the end.

Correct order is:

$\epsilon$-productions → Unit productions → Useless symbols and productions