One Place That Astronomers Think Might Have Had Life Start

Multiple Choice

One place that astronomers think might have had life start long ago is Mars. Which of the following is not a discovery that we have made on Mars so far?

A) observing what looks like dried up river channels from orbiting spacecraft
B) the discovery of organic materials (the chemical building blocks of life, such as amino acids) by spacecraft that have landed
C) the discovery that Mars long ago had plenty of flowing water, from the composition and layering of some of the rocks examined by Mars rovers
D) the discovery of mudstone on Mars, which indicates that ancient Mars may have been more habitable than Mars today
E) the discovery of significant amounts of frozen water on Mars, under the surface