I think it would be the second one because some think that there is enough evidence and some do not.
Mitochondria are unusual organelles. They act as the power plants of the cell, are surrounded by two membranes, and have their own genome. They also divide independently of the cell in which they reside, meaning mitochondrial replication is not coupled to cell division. Some of these features are holdovers from the ancient ancestors of mitochondria, which were likely free-living prokaryotes.
On a giant pasteboard with pictures, and explanation on what each type of engineer.
Reducing sugar is any sugar (all monosaccharides, some disaccharides, oligosaccharides, and polysaccharides) that is capable of acting as a reducing agent because it contains free aldehyde group or free ketone group.
Aldehyde group or alkanal is an organic compound containing formyl group. The formyl group is a functional group consisting of a carbonyl center bonded to hydrogen and an R group. This group can be readily reduced to primary alcohol with the help of catalyctic hydrogenation either applied directly or by transfer hydrogenation.
Ketone group unlike aldehyde group does not have a hydrogen atome bonded to the carbonyl group but it can still be hydrogenated.
6. water vapor fuels a hurricane