PLEASE HELP ASAP: Read the excerpt from "On Becoming an Inventor" by Dean Kamen.

Then Bart went off to college and I had use of the rest of the basement. I stopped doing photography and became interested in electronics. It was the early days of disco, when making music and light shows was the rage. Everyone wanted to buy a box that could connect to their stereo to create new light and sound effects. I started building boxes after school, buying components from a nearby Radio Shack, and reading up on electronic recipes for building loaders in the basement workshop. I began buying voltmeters, soldering irons, and other tools for making light organs to sell at school and in my neighborhood. I made enough money to stock more and more equipment in the family basement.

Which detail shows that Kamen was serious and passionate about his inventions?

Bart left for college and Dean stopped doing photography.
It was the early days of disco and light shows were the rage.
He used the money he made to buy more and more equipment.
Everyone wanted to buy a light box to connect to their stereo.