Option 1 states that both statements are true and that Statement II correctly explains Statement I.

Statement I states that incised meanders are formed in the mature stage of a river. This means that incised meanders occur when a river has reached a certain level of maturity or development.

Statement II states that incised meanders are characterized by rejuvenation and upliftment of land. This means that when a river forms incised meanders, it goes through a process of rejuvenation and upliftment, resulting in the formation of these distinct landforms.

Option 1 suggests that both statements are true and that Statement II correctly explains Statement I. In other words, incised meanders are formed in the mature stage of a river and this formation is characterized by the rejuvenation and upliftment of land.

Therefore, option 1 is correct and the explanation provided in the question is accurate.