Ecosystem productivity is principally limited by

Principally, ecosystem productivity is limited by sunlight and nutrient availability

Sunlight and nutrients are two main ingredients for the plants (which act as the main producer of energy) to produce oxygen and H20 which are very important for the ecosystem

hope this helps

C. gemstones they are the only non metallic mineral from the list.

This is s cute awee : (( . well if she's showing you signs that she may like you , then shoot your shot ! don't be afraid . & if you're unsure that she's giving you these signs , then wait out for a little bit . most girls are different . some may act really sweet , but only bc you're a good friend of hers . that , or she might like you . you just never know . but i think you should sit down with her & tell her how you feel . but don't be awkward & shy . just be straight up & tell her how you feel . if the feelings aren't mutual , then don't cry about it . you need to respect her decision & look for others in the world . feelings can be difficult & confusing , but don't be afraid to show them . i say you play it out & if you're still unsure about it , talk to her . - rach