The introduction of invasive species to an ecosystem can change the dynamic of the among the species.

i am pretty sure it is c because when people are closer together, they cannot move as freely. picture being in a mostly full elevator, for instance. the people are right next to you, and you can barely move.

i would like to make dinner for my mom, dad, and sister

a 2,000 calorie based diet.

one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.