The correct answer is: b) Chants.
Chants are repetitive utterances, typically of a religious nature, that are sung or recited in a monotonous voice. They are often used in meditation and rituals, and can be found in many cultures around the world.
Folk songs are songs that are passed down orally from generation to generation. They are typically associated with a particular region or culture, and often reflect the history and traditions of that group.
Symphonies are large-scale musical works that are typically scored for orchestra. They are composed of multiple movements, and are often based on a particular theme or story.
Ghazals are a type of poem that originated in Persia. They are typically written in a specific meter and rhyme scheme, and often deal with themes of love, loss, and longing.
In the context of Sikkim, the repetitive chants and rhythmic drumming often used for meditation and rituals are referred to as chants. This is because they are typically sung or recited in a monotonous voice, and are often used in religious ceremonies.