I think it is A because they can just destroy it but D is finding something natural to kill it off but it is GM so it wouldn't help so A
Answer: 0.69 m/ mile.
Explanation:
The altitude gradient between two cities X and Y = 
Given: Two cities are separated by 200 miles.
City X has an altitude of 122 meters.
City Y has an altitude of 260 meters.
The altitude gradient between two cities X and Y =

Hence, the altitude gradient between the two cites = 0.69 m/ mile.
Answer:
Major disadvantage to organic farming are discussed below.
Explanation:
The major Disadvantages of Organic farming:
- Organic food is more costly because growers do not receive as much out of their property as traditional farmers get.
- Making charges are more expensive because growers require more extra labor.
- Retailing and shipping are not effective because organic food is grown in smaller quantities.
An adaptation-----------------------
Answer:
Q.1: I can't help you with this, sorry :(
Q.2: Seaweed is the producer because it takes energy from the water and sun in thermal reactions.
Q.3: Phytoplankton is the second-order consumer because they eat first-order consumers.
Q.4: Whelks and crabs because they eat limpets, which eat producers, and they also eat seaweed.
Q.5: Gulls are carnivores because they eat the crabs, and so are crabs because they eat mullets
Q.6: Limpets and lobster would become less populated, but not yet endangered. Gulls would starve and probably disappear from this ecosystem.
Q.7: Whelks' numbers would decrease because of the number of lobsters consuming them, but then lobsters would starve because of the decline in their food. Then this would repeat, shaking the whole ecosystem.