What was one of the challenges dr. salk faced in his attempt to create a polio vaccine? dr. salk did not have enough money to pay for his research and supplies. dr. salk had to create one vaccine that was effective against three different viruses. dr. salk had to convince government officials to allow him to test the vaccine. dr. salk's idea for a vaccine was not supported by other scientists and physicians.

Dr. Salk had to convince government officials to allow him to test the vaccine.

Explanation:

Jonas Edward Salk was a North American physician, virologist and epidemiologist, better known as the inventor of the first anti-polio vaccine.

Salk needed to prove that his vaccine was effective against apoliomelitis, which was a devastating and terrible disease. To test the effectiveness of the vaccine, Salk needed government permission and so had to repeatedly ask government officials to allow him to continue his research and test the vaccines.

i only have part a but here is the first one: - lewis and clark are born

- lewis marries sacajawea and clark is jealous  

- clark drowns lewis and then goes to jail