Tall trees create shade over smaller trees, causing the smaller trees to experience changes in sunlight. Which is most likely a limited resource for the smaller trees?

energy
reproduction
shelter
water

According to theories of how life began, how did early organic molecules begin to separate from the outside world? a: specialized enzymes were required b: chains of amino acids created a barrier c: formation of microspheres or vesicles d: rna catalyzed the formation of membranes