To improve market access, Assam promotes the establishment of:

Self Help Groups (SHGs) are groups of people who come together to save money and access credit. SHGs can help farmers to improve their financial situation, but they do not directly improve market access.

Krishi Vigyan Kendras (KVKs) are agricultural extension centers that provide farmers with training and information on agricultural practices. KVKs can help farmers to improve their productivity, but they do not directly improve market access.

Agricultural Research Institutes (ARIs) are research centers that conduct research on agricultural issues. ARIs can help to develop new agricultural technologies, but they do not directly improve market access.

In conclusion, the correct answer is: a) Farmer Producer Organizations (FPO).