How are casts formed by decaying organisms? Organisms turn into rock over time.
Organisms leave carbon residue on a rock.
Organisms leave impressions in sediment that hardens into rock.
Impressions left by organisms are filled in with sediment that hardens into rock.

D.Impressions left by organisms are filled in with sediment that hardens into rock.

the answer is; comparing the frequency of collisions with and without the device

this makes the anti-collision system an independent variable and the collisions a dependent variable. if there are fewer collisions with an anti-collision system that without, then it can be stated that the system is a success. essentially, collisions under an anti-collision system are compared with the frequency of collisions by cars with the human drivers.

the answer is admiramos

the rule for verbs is whoever you are referring to (in this case 'nosotros'), you need to change the ending of the word.

nosotros - amos

yo - o

tu - as

el, ella, usted - a

ellos, ellas, ustedes - an

(examples: nosotros bailamos (instead of bailar) or yo hablo (instead of habla)