First, let's calculate the mean of the given set.
The mean is given by the sum of all numbers divided by the amount of numbers:
![\begin{gathered} mean=(122+130+145+154+165+178)/(6)\\ \\ mean=(894)/(6)\\ \\ mean=149 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/y4a2bltwgvuckld6ctkugdhwd5yeothp7s.png)
In order to increase the mean, we need to add a number that is greater than the mean.
Looking at the options, the only number that is greater than the mean is 150.
Therefore the correct option is D.