Answer:
1. improved the sewing machine - Isaac Singer
2. studied and wrote about birds - John J. Audubon
3. invented the telephone - Alexander Graham Bell
4. invented the wireless - Guglielmo Marconi
Explanation:
Singer is famous for improving the sewing machine and established Singer Sewing Machine Company
Audubon is the famous American ornithologist who was researching about bird species.
Bell was a famous American inventor who invented telephone in 1876.
Marconi was one the most famous inventors of first half of 20th Century, who won Nobel Prize for his work.
