The answer is "d. her nationality".
Variables are dichotomous on the off chance that they have precisely two particular values, for example, sex or being married. They are dissected uniquely in contrast to different factors. A dichotomous variable is one that goes up against one of just two conceivable esteems when watched or estimated. The value is frequently a portrayal for a deliberate variable (e.g., age: under 70/70 and over) or a characteristic (e.g., sex: male/female).