Final answer:
It is true that Earth and Venus initially outgassed similar amounts of carbon dioxide, but Earth was able to lock much of it in the oceans and rocks, a process facilitated by water and life, unlike Venus.
Step-by-step explanation:
The statement that Earth initially outgassed as much carbon dioxide as Venus but has it locked up in the oceans and rocks is true. Earth's carbon dioxide is largely sequestered in sedimentary rocks as calcium and magnesium carbonates and is also found in the oceans primarily as bicarbonate ions (HCO3-). The processes of weathering and life, particularly photosynthesis, further reduce atmospheric CO2. Over time, Venus lost its water, which acted as a vital component in trapping carbon dioxide. In the absence of water and life to facilitate these processes, Venus's atmosphere ended up with much higher levels of carbon dioxide. Moreover, with increasing solar luminosity, Earth has developed a delicate balance where the faster weathering of rocks has helped keep its climate stable and conducive to complex life forms by removing excess carbon dioxide from the atmosphere. This has not been the case for Venus, leading to its current state with a thick atmosphere rich in carbon dioxide.