There are two types of variables which are used for scientific experiments.
Dependent variable
Independent variable
A dependent variable can be described as the variable which is being measured or tested in an experiment. An independent variable can be described as the variable which is changed in the experiment to check if it has any effects on the dependent variable. An independent variable is the one which can be controlled.
The answer is a C. The offsprings from this generation are from a cross between parents who are heterozygous (one parent) and homozygous recessive. This means that all the offsprings of the filial 1 (one) generation will carry a recessive allele. However, those with an equivalent dominant allele will not exhibit the attached earlobe trait. This is shown by the Punnet square below;
