By explaining problems and giving solutions! this is the best fit because the other two might make sense at a first glance, but only explaining problems and solutions would be an effective way to teach people how to set up an aquarium by giving them examples of what to do and what not to do whereas the others are just him talking about his aquarium.
<span>What did Mark Twain dream of becoming when he was a boy?
</span>a deckhand
Answer: involving two political parties
Answer: Technology
Explanation: There are so many ways and techniques technology has created for everyone. Especially those with disabilities and physical injuries. Lots of training and adapting. Robotic legs, caste, etc. A lot of things can help
OR is the coordinating conduction in the sentence