"necessary option" is a correct and usable phrase in written English.
It can be used in a sentence to refer to a required choice or alternative. Example: It is important to carefully consider all necessary options before making a decision. Here, "necessary option" means the available or required choices that must be considered before making a decision.
Loans are sometimes a necessary option to help meet educational expenses.
As long ago as the 1970s, Egyptian leaders declared that dwindling oil reserves would make nuclear power a necessary option.
In order to overcome these challenges, an efficient video allocation algorithm is a desirable and necessary option.
He's also a necessary option, given that the first choice midfield partner for Bradley, Jermaine Jones, is prone to yellow cards.
Mr. Chen said that law enforcement authorities insisted that residential detention was a necessary option because the police needed more time to investigate certain cases.
By that time, said Jeanne Fox, regional E.P.A. administrator, the extent of the contamination had been found to be greater than originally thought, and excavation and removal looked more like a cost-efficient and necessary option.
The summit statement said EU leaders would "examine all necessary options" to protect civilians.
"All necessary options is strong language," he said, referring to the formula agreed for the joint statement.
Some diplomats hope that by talking of "all necessary options" they can deter further attacks by Colonel Qaddafi.
In order to protect the civilian population, member states will examine all necessary options, provided there is demonstrable need, a clear legal basis and support from the region".
Of course they did: it hovers brooding and baleful over every Pentagon and EU planning table as the empty talk of "all necessary options" trundles along.
