German scientists were concerned about nazi restrictions on uranium sales because

a. uranium would not be available for industrial research.
b. uranium was important to german missile programs.
c. uranium paid for german scientific research.
d. uranium could be used in research on atomic weapons.

d.uranium could be used in research on atomic weapons.

Explanation:

The first nuclear bomb ever made relied of the fission reaction of Uranium.

Nuclear fission is a radioactive active decay in which an unstable large radioactive atom splits into smaller nuclei with the release of tonnes of energy.

²³⁵U absorbs neutrons to become ²³⁶U which then splits into ⁹²Kr and ¹⁴¹Ba, and releases gamma rays and a large disproportionate amount of energy.

This made the German scientists concerned about Nazi restrictions on uranium sales.

c (diamond),

sio2 (quartz)