Which novelist, Irène Némirovsky or Michael Frayn, wrote primarily in French?
Irène Némirovsky: Irène Némirovsky (] ; 24 February 1903 – 17 August 1942) was a novelist of Ukrainian Jewish origin born in Kiev Ukraine under the Russian Empire; she lived more than half her life in France and wrote in French, but was denied French citizenship. Michael Frayn:  His novels, such as "Towards the End of the Morning", "Headlong" and "Spies", have also been critical and commercial successes, making him one of the handful of writers in the English language to succeed in both drama and prose fiction.
Irène Némirovsky