The primary effect of global warming that corresponds to your options is "rising sea level over a period of time." This effect is a direct consequence of increasing greenhouse gas concentrations in the atmosphere, which leads to climate change. As global temperatures rise, polar ice melts and ocean waters expand, contributing to higher sea levels.
The other options, such as changing seasons every year and increasing carbon dioxide in the atmosphere, are related effects but are not direct outcomes in the way that rising sea levels are. Increasing carbon dioxide is a cause of global warming rather than an effect, and while seasonal changes may be observed, they are not as direct or as universally impactful as rising sea levels.