Final answer:
Ethidium bromide is known to cause frameshift mutations as it is an intercalating agent that creates abnormally spaced base pairs, leading to insertions or deletions during DNA replication that change the genetic code's reading frame.
Step-by-step explanation:
Frameshift mutations can result from various molecular mechanisms. Among the options provided, ethidium bromide is known to cause frameshift mutations as an intercalating agent. Intercalating agents like ethidium bromide slide between the stacked nitrogenous bases of DNA, causing abnormal spacing between base pairs. This distortion can lead to insertions or deletions during DNA replication, resulting in a frameshift mutation.
Other mechanisms such as alkylating agents might mainly lead to point mutations by adding alkyl groups to DNA, tautomeric shifts can cause base-pair mismatches, base analogs can be incorporated into DNA in place of normal bases leading to point mutations, and deamination which changes cytosine to uracil could result in point mutations. Frameshift mutations are serious because they change the reading frame of the genetic code, which alters every subsequent codon and often results in nonfunctional proteins, having severe biological consequences.