Answer:
C
Explanation:
expediency def: the quality of being convenient and practical despite possibly being improper or immoral; convenience
It doesn't make since with the sentence
B. They are spies for the Nazis, and Anne suspects this.
Biology does influence gender development. For example, some differences between typical boys and girls can be explained by the effect of genes on sex chromosomes, and by the levels of sex hormones and their effect on the brain during early development (e.g., prenatal exposure to high levels of male-typical hormones).