The correct answer is: B. Genetically fixed
An ecotype is a geographically isolated population of a species that has adapted to its specific environment through genetic changes. These changes are passed down from generation to generation, making them genetically fixed.
Option A is incorrect because environmentally induced variations are not always temporary. For example, if a population of plants is exposed to a drought, the plants that are able to survive and reproduce will have genes that make them more drought-tolerant. These genes will be passed down to the next generation, and the population will become genetically adapted to drought.
Option C is incorrect because environmentally induced variations can be genetically related. For example, if a population of animals is exposed to a new predator, the animals that are able to escape will be more likely to survive and reproduce. These animals will have genes that make them better at escaping predators, and these genes will be passed down to the next generation. Over time, the population will become genetically adapted to the new predator.
Option D is incorrect because ecotypes are a type of species.