Final answer:
The prevailing hypothesis, known as the RNA world hypothesis, suggests that RNA may have been the first organic molecule to evolve, and that early life was based on RNA. RNA can encode genetic instructions and carry out chemical reactions, solving the problem of which came first, DNA or proteins.
Step-by-step explanation:
The prevailing hypothesis about why RNAi evolved is known as the RNA world hypothesis. This hypothesis suggests that RNA may have been the first organic molecule to evolve, and that early life was based solely on RNA before the emergence of DNA and proteins. RNA is capable of encoding genetic instructions like DNA, and some RNAs can also carry out chemical reactions like proteins. The RNA world hypothesis solves the problem of which molecule, DNA or proteins, came first in the early stages of life.