The conservation of tillage practices leads to agricultural sustainability by protecting the farmer's crops from insects and other pests, thus, it reduces the need for the farmers to buy pesticides for the crops, since the tillage method prevents insects.
An enormous cloud of gas and dust that contracts due to gravity and forms stars is called a nebula.
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.
Answer:
5 bases
Explanation:
If there are 17 amino acids and only 2 bases that can be combined in order to make a codon then:
for 4 bases 
is 16 and it is not enough combination for all 17 amino acids
for 5 bases 
is 25 combinations (meaning that more than one codon could code for the same amino acid).
The answer would NOT be B for this question.
Knowing myself the answer would be A because nuclear energy would be an alternate source of energy unlike natural gas.
