The correct answer is: a) Tropical evergreen forests.
Tropical evergreen forests are the most common type of forest in Assam. They are characterized by their dense canopy of trees that remain green all year round. These forests are home to a wide variety of plant and animal life, including many species that are found nowhere else in the world.
Deciduous forests are found in temperate climates, where there is a distinct change in seasons. The trees in these forests lose their leaves in the fall and grow new ones in the spring. Deciduous forests are not as common in Assam as tropical evergreen forests, but they can be found in some parts of the state.
Alpine forests are found in high mountains, where the climate is cold and dry. The trees in these forests are short and stunted, and they have adapted to the harsh conditions by growing thick bark and needles instead of leaves. Alpine forests are not found in Assam.
Mangrove forests are found in tropical and subtropical coastal areas. The trees in these forests are adapted to live in salty water, and they have roots that grow above the ground to help them breathe. Mangrove forests are not found in Assam.