Which of the following represent human systems?
hoover dam
genetic engineering
volcanic eruptions
the panama canal
plate tectonics

Option (2)

Explanation:

Genetic engineering is defined as a process by which a DNA (or other molecules of nucleic acid) can be artificially operated, alter and recombined so that an organism can be modified. In addition to this, modification of gene and cloning can also be done. This a human-operated system.

Genetic engineering is directly based on the study of a DNA, which is present inside the body of an organism, so it is considered as a human system.

Hoover Dam and the Panama canal are both human-made structures. Plate tectonics is a geological process that leads to the eruption of volcanoes and is a natural process.

Thus, the correct answer is option (2).