Correct Answer: Option D - All are correct
Kannur has the longest coastline among Kerala's districts - This is correct. Kannur district has approximately 95 km of coastline, which is the longest among all of Kerala's districts.
Kollam has the least length of coastline among the coastal districts - This is correct. Among Kerala's nine coastal districts (Thiruvananthapuram, Kollam, Alappuzha, Ernakulam, Thrissur, Malappuram, Kozhikode, Kannur, and Kasaragod), Kollam has the shortest coastline at approximately 37 km.
Wayanad is a non-coastal district - This is correct. Wayanad is an inland district located in the northeastern part of Kerala in the Western Ghats. It does not have any coastline as it is completely landlocked. The other non-coastal districts in Kerala are Palakkad, Idukki, Kottayam, and Pathanamthitta.