Answer and Step-by-step explanation:
a. Yes, since the highest standard deviation (s4 = 44.51) is significantly more than double the lowest (s3 = 20.83) is plausible.
hence, the second option is correct
(b) The testing of relevant hypothesis using the output is shown below:
As we see that
The 0.05 is more than the F test P-value i.e 0.0000
So ultimately P-value is less
Therefore we have to reject the null hypothesis
Since p-value is less than 0.05 so we reject the null hypothesis.
Therefore, the third option is correct
(c) The construction is shown below:
Since the sample size is the same so for Tuley's HSD it would also same i.e for each pair
Now Tuley's HSD is

The table that reflects the difference in means in different level is as follows
Levels Difference in mean
4-6 34.85
4-8 41.92
4-10 74.15
4-12 103.96
6-8 7.07
6-10 39.3
6-12 69.11
8-10 32.23
8-12 62.04
10-12 29.81
Now the table of significant difference is
Levels Difference in mean
4-10 74.15
4-12 103.96
6-12 69.11
8-12 62.04