Which of the following agricultural techniques requires more and more land to be cleared every two years due to soil exhaustion?
a)swideen agriculture
b)terraced farming
c)wet rice agriculture
d)dry rice agriculture

Altocumulus, altostratus, cirrocumuls, cirrostratus, cirrus, cumulonimbus, cumulus, nimbostratus, stratocumulus, stratus 8.) clouds with tallest vertical development 9.) low altitude clouds in solid layers that produce rain 10.) high altitude thin flat layers of clouds 11.) rain clouds that form under stable atmospheric conditions 12.) middle altitude clouds with globular appearance