Given the task definition and input, reply with output. In this task, you're given a question, a context passage, and four options which are terms from the passage. After reading a passage, you will get a brief understanding of the terms. Your job is to determine by searching and reading further information of which term you can answer the question. Indicate your choice as 'a', 'b', 'c', or 'd'. If you think more than one option is plausible, choose the more probable option to help you answer the question.

Question: What country is Gasaton Cros' birthplace now found? Passage:Colonel Marie Augstin Gaston Cros (known as Gaston Cros) (6 October 1861 10 May 1915) was a French army officer and archaeologist. He was born in Alsace and was displaced when that territory was incorporated into the German Empire. He joined the French Army as a lieutenant and saw action in Tonkin before spending several years surveying in Tunisia, receiving the honours of membership of Vietnamese and Tunisian orders and appointment as a chevalier of the Legion of Honour. In 1901 Cros was appointed head of the French archaeological expedition to Girsu, Iraq to continue the work of Ernest de Sarzec. His work over the next five years included the tracing of the thick city wall and for his work there received a letter of commendation from Gaston Doumergue, the Minister of Fine Arts, and the award of the Golden Palms of the Ordre des Palmes Academiques. Promoted to lieutenant-colonel, Cros served in the French protectorate of Morocco from 1913, seeing action in the Zaian War.
Links: a. Alsace b. Tunisia c. Alsace d. Girsu
a