Option 1 is the River Indus. The River Indus is one of the longest rivers in Asia, but it is not the longest. It flows through Pakistan and enters the Arabian Sea.

Option 2 is the River Yangtze. This is the correct answer. The River Yangtze is the longest river in Asia and the third-longest in the world. It flows through China and has a length of about 6,300 kilometers.

Option 3 is the River Hwang Ho, also known as the Yellow River. The River Hwang Ho is the second-longest river in Asia, but it is not the longest.

Option 4 is the River Ganga, also known as the Ganges. The River Ganga is one of the major rivers in Asia, but it is not the longest.

Therefore, the correct answer is option 2, the River Yangtze. It is important to note that the length of rivers can vary depending on different sources and interpretations, but the River Yangtze is generally considered to be the longest river in Asia.