What is a mineral reserve? Choose one: A. known quantities of minerals still in the ground B. particular minerals needed for strategic purposes in a country C. a supply of minerals kept for future generations D. minerals that countries keep for themselves and do not exportWhy do estimates of mineral reserves change? Choose one or more: A. Reserves change as resources become contaminated and unusable. B. Reserves change as resources are depleted. C. Reserves change as prices rise, making advances in mining worth the cost. D. Reserves change when more minerals are formed and scientists recalculate the resource. E. Reserves change when previously unknown resources are discovered