Why do so many geneticists focus on studying yeast, fruit flies, nematodes, mice or the small plant arabidopsis?

They are all genetically tractable

Explanation:

Yeast, fruit flies, nematodes, mice or the small plant Arabidopsis have known genome i.e their entire genetic information is known to the scientific community, thus they are EASILY MODIFIED in genetic research.

Also, they are simple eukaryotes (having cells with defined nucleus) so they can explain the processes in the human eukaryotic cell during genetic research

Both reasons make them genetically tractable

1. (1.2kw)x(15/60hours) = .3kwh --> a

2. (5kw)x(90/60hours)x(8cents/kwh) = $0.60 --> d

3. microwave --> 1200 watts = (1.2kw)x(6/60hours) = .12kwh

coffee-maker --> 900 watts = (.9kw)x(10/60hours) = .15kwh

therefore, it requires more energy for the coffee-maker to do the same amount of work.

so the answer is a.

halogen, any of the six nonmetallic elements that constitute group 17 (group viia) of the periodic table. the halogen elements are fluorine (f), chlorine (cl), bromine (br), iodine (i), astatine (at), and tennessine (ts).