What type of flute is considered a traditional vertical woodwind instrument in South America?

The Tarkas is recognized as a traditional vertical woodwind instrument in South America, particularly among the indigenous cultures of the Andes. It is typically made from bamboo or wood and is characterized by its distinctive vertical playing position, where the musician blows air through the top of the instrument. The Tarkas not only features unique haunting tones but also plays a significant role in cultural rituals and celebrations within these communities.

In contrast, the Ocarina is more of an earthenware wind instrument often shaped like an animal, the Siku is a type of pan flute that consists of multiple pipes, and the Rasp is a percussion instrument. Each of these options you might consider does not align with the definition of a vertical flute. Thus, the Tarkas stands out as the appropriate answer in identifying a traditional South American vertical woodwind instrument.