I believe your answer would be the stem.
Answer:
selective breeding; biotechnology
Explanation:
Selective breeding is a type of artificial selection that consists of crossing plants/animals with desirable and heritable phenotypic traits in order to increase the frequency of such traits in progeny. Selective breeding can be considered as one of the first biotechnological techniques applied by humans. In the past, the selective breeding technique has allowed obtaining domesticated animals (e.g., dogs from wild wolves) and domesticated crops from their wild ancestors (e.g., maize from its wild ancestor teosinte).
Vestigial structures are inherited from ancestors, but have lost much or all of their original function due to different selection pressures acting on the descendant. The hipbones of bottlenose dolphins are vestigial structures. However, as the dolphin lineage adapted to life at sea, this function was lost.
Answer;
-B3
Explanation;
Refrigerants are divided into two groups according to toxicity:
-Class A signifies refrigerants for which toxicity has not been identified at concentrations less than or equal to 400 ppm; and
-Class B signifies refrigerants for which there is evidence of toxicity at concentrations below 400 ppm.
They are also divided into three groups according to flammability:
-Class 1 indicates refrigerants that do not show flame propagation when tested in air at 21°C and 101 kPa;
-Class 2 indicates refrigerants having a lower flammability limit of more than 0.10 kg/m3 at 21°C and 101 kPa and a heat of combustion of less than 19 kJ/kg;
-Class 3 indicates refrigerants that are highly flammable as defined by a lower flammability limit of less than or equal to 0.10 kg/m3 at 21°C and 101 kPa or a heat of combustion greater than or equal to 19 kJ/kg.
-Therefore; the answer for the above question would be Class B and class 3.
