Answer
The results are ambiguous. We can conclude that $µ_{No~Drug}\neµ_{Experimental~Drug~2}$, but we could not conclude that $µ_{No~Drug}\neµ_{Experimental~Drug~1}$ or that $µ_{Experimental~Drug~1}\neµ_{Experimental~Drug~2}$.
There is at least one Type II error (when we do not reject $H_0$ when we should have rejected).
Work Step by Step
With the results from item (a) still available:
Select Stat -> ANOVA -> General Linear Model -> Comparisons
In Response select C3. In Type of comparison select Pairwise. In Method select Tukey. In Choose terms for comparisons select C2 (treatmeants).
Click OK.
