In a study, you ask the subjects their gender. Is this data qualitative or quantitative?

Step 1 
Qualitative and quantitative data: 
Qualitative data: 
Qualitative variable categories each individual to corresponding groups. It is used for classification of individuals based on some attributes or qualities or characteristics. Categorical variable is also called as qualitative variable or nominal variable. In other words, a categorical or qualitative variable is one that is used for classification of individuals based on some attributes, qualities, or characteristics.
Qualitative data are non-numerical measures such as characteristics, attributes or labels. 
Quantitative data: 
A variable that provides numerical values of individual and Arithmetic operations such as addition and subtraction produce meaningful results are called quantitative variables. A quantitative data contains measured numerical values with measurement units. 
Step 2 
Justify whether the data corresponding to the subjects' gender is qualitative or quantitative:
Here, the investigator asks the subjects about their gender and notes the gender of the respective subjects. 
In general it is known that the gender will be in three types. That is: male, female and transgender. 
The investigator categorizes the gender, which do not take natural numerical values. Even if some numerical values are assigned to this variable gender, such as (0 for transgender, 1 for male, 2 for female), arithmetic operations (addition, subtraction) on these values are meaningless. Thus, the variable gender is categorical or qualitative. The dataset of the qualitative variable will be qualitative dataset. 
The investigator's entire dataset contains male, female, and transgender individuals. This is a feature of the subjects.
Therefore, the data corresponding to gender of the subjects is a qualitative. 
Step 3 
Result: 
The data corresponding to gender of the subjects is a qualitative data.