Fruit flies produce offspring relatively fast and have specific traits, such as eye color and body color/shape. They are easy to observe and their traits are easily traced throughout the next generations.
Alternative energy sources are those that do not deplete natural resources and do not harm the environment.
Options A, B, and C are all fossil fuels, which we know can be depleted and harm the environment.
The only valid option here is D, Geothermal energy.
Geothermal energy is both renewable and environmentally friendly.
Homozygous means that it has the same alleles and lower case represents a recessive trait therefore the genotype for a homozygous recessive individual is: bb