List all metalloids on the periodic table

In terms of alternation of generations, the internal parts of the pollen grains of seed-producing plants are most similar to a ) moss sporophyteb) moss gametophyte bearing both male and female gametangiac) fern sporophyted) fern gametophyte bearing only antheridia

Which statement explains how gravity and intertia work together

Ascientific idea becomes valid when it is what?