Which treeless alpine biome above the tree line is home to pikas and mountain goats?

The treeless alpine biome above the tree line that is home to pikas and mountain goats is the alpine tundra.

Alpine tundra occurs at high elevations where cold temperatures, strong winds, a short growing season, and shallow soils prevent trees from surviving. It can be found in mountain ranges including the Rockies, Alps, Andes, Himalayas, and Scandinavian Mountains. The upper boundary generally approaches the permanent snow line.

Plants are typically low-growing, including grasses, sedges, mosses, lichens, cushion plants, and dwarf shrubs. Animals such as pikas and marmots gather or store vegetation, while mountain goats and bighorn sheep navigate rocky slopes. The exact animal community varies by continent, so no single species lives in every alpine tundra region.

Alpine tundra is often confused with Arctic tundra. Arctic tundra is defined mainly by high latitude, whereas alpine tundra is defined by high elevation. Chaparral is a shrubland, steppe is a mostly dry grassland, and neither is the best answer here.