Answer:
I believe it would be these:
He can replace the 1.5-volt battery with a battery of higher voltage.
He can use a longer piece of wire that wraps more times around the bolt.
I'm not sure the others would work
An invasive species, such as the trees in your question, could:
- Out compete the native flora for resources, such as nutrients.
- An earlier reproductive and faster growing cycle could quickly surpass native tree growth.
- This alien species taking the place of native trees could disrupt the habitat of animal species that need the native flora instead.
Jobs.... they do different jobs.