The correct answer is - D. A drought kills all the plants in an area, leaving bare land.
If there's such a big drought that will manage to kill off all the vegetation in an area and leave bare land behind it, than the land will be degraded in no time. Once the land is left without its natural protection that the roots of the vegetation provide, the land will be exposed to high rates of and erosion. The erosion will be very quick and the top layers of the soil will be moved away with every wind and rainfall that will appear. That will degrade the land to a very high degree, making it totally unusable and it will need lot of time to eventually recuperate.
Lipids are fatty substances thus they release greatest amount of energy more than carbohydrates
If you used a full active virus, that defeats the point of a vaccine. You will trigger your immune response, but since you would just be injecting the virus, it will make you sick, and your body will be less effective at fighting the pathogens.
Viruses in vaccines are weakened, so they essentially will not "fight" back. They most importantly just contains the antigen markers so the body can trigger the immune response, quickly eradicate the pathogen, and build up the memory cells to that virus.
Injecting a virus that is not weak will just be the same thing as if you got the virus, you will likely get sick.
