In the question, the sentence has two blanks: each blank indicating that something has been omitted. Choose the set of words for the blanks which best fits the meaning of the sentence as a whole.
"The ______ of new projects in the energy sector is ______ not only on low cost or profitability of the project but also on sustainability".

The pair of words that most appropriately completes the sentence is initiation and dependent. This is due to the fact that initiation pertains to the beginning or start of new ventures. Additionally, "is dependent on" is a frequently used phrasing that indicates something relies on various factors, which fits the context of projects being affected by cost, profitability, and sustainability.

So, option-C is the correct answer.