The correct answer is: c) Shown significant improvement in recent decades.
According to the 2011 census, the literacy rate in Arunachal Pradesh was 65.38%, up from 52.83% in 2001. This represents an increase of 22.55 percentage points, or 42.2%. This is a significant improvement, and is likely due to a number of factors, including increased access to education, government initiatives to promote literacy, and a growing awareness of the importance of education.
The literacy rate in Arunachal Pradesh is still lower than the national average of 74.04%, but it is improving at a faster rate. This is encouraging, and suggests that the state is making progress in terms of education.
Option a) is incorrect because the literacy rate in Arunachal Pradesh has been increasing in recent decades.
Option b) is incorrect because the literacy rate in Arunachal Pradesh has not remained stagnant in recent decades.
Option d) is incorrect because the literacy rate in Arunachal Pradesh has not reached 100%.