According to the u. s. census bureau, philadelphia had a population density of 11,379.5 people per square mile in 2010, while the entire u. s. had a population density of 87.4 people per square mile. which best explains the contrast between these two population densities?
while most areas of the u. s. have a high population density, the u. s. encompasses a vast amount of land.
the birthrate decreased throughout the u. s.
while some areas of the u. s. have a high population density, others must have extremely low population densities.
all of the above are correct.

The gene that causes sickle-cell disease is present in a higher percentage of residents of sub-saharan africa than among those of african descent living in the united states. even though this gene causes sickle-cell disease, it also provides some protection from malaria, a serious disease that is widespread in sub-saharan africa but absent in the united states. discuss an evolutionary process that could account for the different percentages of the sickle-cell gene among residents of the two regions.

Imagine ? person stepping on a pin and pulling his or her foot way look at the réfléchir arc of the scenarios below

Getting out of bed is the first goal i tackle each day. 2several small goals are achieved by me as the day progresses. 3when i am riding the bus home or walking the dog, i think about the bigger goals i have for my life. which statement correctly describes the verb tense, aspect, and voice in this paragraph? a.sentences 1 and 2 contain present progressive verbs. sentence 3 contains both present progressive and simple present verbs. sentence 2 uses passive voice. b.sentences 1 and 2 contain simple present verbs. sentence 3 contains present progressive verbs. all three sentences use active voice. c.sentences 1 and 2 contain present progressive verbs. sentence 3 contains simple present verbs. all three sentences use active voice. d.sentences 1 and 2 contain simple present verbs. sentence 3 contains both present progressive and simple present verbs. sentence 2 uses passive voice.