"The incredible diversity of pterosaurs is perhaps best expressed in one of the prehistoric flying reptile's most intriguing and mysterious features: the head crest."
What evidence from the text supports the idea that the diversity of pterosaurs is best
expressed in their head crests?
A "Many pterosaurs had flesh-and-bone crests atop their skulls - dramatic
anatomical characteristics whose purpose is still debated by paleontologists."
B "Akin to a rooster's comb, peacock's crown, or the frill on some lizards!
necks, pterosaur crests were prominent anatomical features found across many
species."
C "Pterosaurs crests are thought to have been fairly ubiquitous, appearing in
many groups of pterosaurs from the Triassic (252-201 million years ago)
through the Jurassic (201–145 million years ago) and Cretaceous (145-66
million years ago) periods."
D "Among pterosaur species known to have had crests, there is an amazing
range of shapes and sizes."

the answer is:  

line graphs show patterns in data with variables that change over time; whereas, circle graphs show data as parts out of a whole (such as out of 100%).

the seeing the electronic configuration we can say that the element is fluorine.

fluorine is the most electronegative element in the periodic table.

but by only seeing the configuration we cannot say about its reactivity because we don't know if its configuration after excitation or by addition of electrons.

but if not then, it is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. as the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.

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the population of unionid mussels in the hudson river decreased after zebra mussels were introduced. zebra mussels, a nonnative species, competed with the unionid mussels for food. the zebra mussels were able to outcompete the unionid mussels, allowing the zebra mussel population to increase dramatically over six years. the unionid mussel population decreased due to a lack of food.

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