4. Thinning ozone levels may cause: A. Acceleration of photosynthesis in plants
B. Increased exposure to ultraviolet radiation on Earth
O C. Alien domination
O D. Disruption of radio signals from Mars

B

Explanation:

humans will be overly exposed to strong UV light. UV light causes skin cancer, cataracts, sunburns, weakening of the immune system and quick aging.

in the year 2850, humans successfully colonized mars. the martian modules that were constructed could hold only a small population of people. it is now a century later, and the population on mars has grown to 600 people. of the current mars population, 45 people express the recessive phenotype for phenylketon- uria (pku) syndrome (pp genotype).

explanation: