Which of the following is a highly speculative issue about the early origin of life?

A) Sufficient evidence exists that RNA might have been the first informational molecule.
B) Amino acids could have originated by Krebs cycle acids complexed to a dinucleotide.
C) Bacterial redox metabolism can be evidenced through ³⁴S/³²S ratios from 3.47 Gyr ago.
D) Ancestors of methanogens using H₂ and CO₂ to make CH₄ and H₂O evolved early.
E) Panspermia, life forms originated elsewhere, were seeded on Earth by meteorites.