Read the given assertion and reason and choose the correct option.
Assertion [A]: Global warming reduces pH levels in the oceans.
Reason [R]: Carbon dioxide dissolves in water to form carbonic acid.
Global warming is mainly caused by an increase in the levels of greenhouse gases such as carbon dioxide and methane in the atmosphere. Carbon dioxide dissolves in water to form carbonic acid. This would result in an apparent decrease in pH levels in the oceans, adversely affecting marine life.