Please help! will give brainlist!

Which best describes the digestive system of arthropods? a incomplete, two openings b complete, one opening c two-way, one opening d one-way, two openings

Hurry which of these is true about index fossils? a) are very scarcely found b) used as guides in relative dating c) found in the youngest layer of the rock d) used as reference points in absolute dating

Drag each label to the correct location in the equation. not all tiles will be used. the density of mercury is 13.6 grams per cubic centimeter. complete the steps for converting 13.6 g/cm3 to kg/m3. (1 kg = 1,000 g, 1 m3 = 106 cm3)