Final answer:
The first true cells on Earth were indeed anaerobic, as they evolved in an early anoxic atmosphere and were of the prokaryotic type, which does not require oxygen to survive.
Step-by-step explanation:
The statement that the first true cells were most likely anaerobic is true. Early Earth's atmosphere was anoxic, lacking molecular oxygen, which implies that the first organisms to evolve needed to survive without oxygen. The fossil record and genetic evidence both point to prokaryotic cells as Earth's earliest life forms, originating around 3.5 billion years ago. These prokaryotes were capable of functioning and thriving in an anoxic environment. Eventually, photosynthesis evolved in some of these organisms, such as cyanobacteria, leading to the production of oxygen as a byproduct. This process paved the way for the eventual oxygenation of Earth's atmosphere, allowing aerobic life forms to emerge.