Final answer:
UV light limits microbial growth by causing the formation of thymine dimers in DNA, leading to mutations that inhibit protein synthesis and can kill the microorganisms.
Step-by-step explanation:
UV light can limit microbial growth by inducing lethal mutations in the microorganisms' DNA. Specifically, UV light causes the formation of thymine dimers within the DNA strand, which can lead to errors when the DNA is replicated. This is because when DNA polymerase encounters a thymine dimer, it may not incorporate the corresponding complementary nucleotides correctly, resulting in mutations. Over time, these mutations can accumulate and kill the microorganism. Therefore, the correct answer to how UV light can limit microbial growth is B) By inhibiting protein synthesis, since DNA damage and mutation can prevent the proper synthesis of proteins essential for cell survival.