What causes convection currents to occur on earth? A. Cool air rising, warm air sinking

B. Cool air rising, but warm air rising

C. Warm air rising, cool air sinking

D. Warm air sinking, cool air sinking

Linda and julia are trying to determine whether their ideas are scientific or pseudoscientific. linda's idea is free of bias. julia's idea gives the same result when tested repeatedly. which statement is correct about linda and julia's idea?