Answer:
a. continue with the project provided that the additional solar electricity is worth more than $10 million.
Explanation:
It is provided that after cost overruns of the project is $10 million, which can never be recovered, thus, it is a kind of sunk cost.
Sunk cost is the cost which is made previously, and now in no manner will affect the decision, as cannot be recovered.
Therefore, such cost is ignored.
Further provided additional cost will be $12 million, therefore, now the society shall make a rational choice whether to continue the project providing solar electricity of $10 million, as in case of amount of solar energy is $32 million or $22 million, then the choice is obvious to accept,
Rational choice will be for solar electricity worth $10 million.
Therefore, correct statement is
a. continue with the project provided that the additional solar electricity is worth more than $10 million.