While I am the fastest to conduct research design, one big disadvantage I have is that I do not generate information about the development of individuals. Which research method am I?

Cross-sectional research method

Explanation:

The cross-section research design is most widely used in healthcare based researches. It is type of descriptive research based on observational studies.  

This research is usually done on a group of people and provides both qualitative (descriptive interpretations) and quantitative (statistical interferences) details.  

This research is not a relational type of research and hence cannot be used to study, relate or compare about individual changes. The experiences, values, changes observed in individual cases are not taken into consideration.

For example, it is used to study a disease like cancer in a certain group or a population-based on variables like different sex, age religion, ethnicities, location etc of various people. It is not used to study about cancer in an individual person.

It is also not the causal type and cannot be used for cause and effect type of researches. Manipulation of variables is not possible with this research design.  

multiple allele inheritance is traits controlled by more than 2 alleles (ex: pigeons having 3 alleles of one gene govern their feather color).   so the answer is a.