The correct answer is a) Alappuzha.
The Scheduled Tribes (STs) are a group of people who are considered to be indigenous to India. They are officially recognized by the Indian government and have certain rights and privileges that are not available to other groups of people.
The ST population in Kerala is relatively small, making up only about 1% of the total population. The district with the least concentration of ST population is Alappuzha, with only about 0.5% of the population belonging to this group.
The other options are incorrect because they all have a higher concentration of ST population than Alappuzha. Kannur has about 1.5% of its population belonging to the ST group, Kasaragod has about 2%, and Kollam has about 2.5%.
The ST population in Kerala is concentrated in the northern and northeastern parts of the state. The districts with the highest concentration of ST population are Wayanad, Malappuram, and Kozhikode. These districts are home to a number of tribal groups, including the Adivasi, the Kurumba, and the Irula.
The ST population in Kerala faces a number of challenges, including poverty, illiteracy, and lack of access to basic services. The government has taken a number of steps to address these challenges, but there is still a long way to go.