The helping verbs are has, have had, do, does, did, be, am, is, are, was, were, been, can, could, shall, should, will, would, may, ... C - has the helping verb -- and is a VERY BADLY ...
This is how to solve the problem:
We know that the growth rate is constant for both species of plants. So we can say that the height is a linear function of the number of days since d = 0.
Assumption (1 month = 30 days)
Species A:
Growth rate = 2 cm/month = 2/30 = 1/15 cm/day
Height on day d = 0: 12 cm
Height: H(d) = 12 + d/15
Species B:
Growth rate = 3 cm/month = 3/30 = 1/10 cm/day
Height on day d = 0: 10 cm
Height: H(d) = 10 + d/10
We can actually deduce here that the sentence from the passage that indicates that the source is not entirely credible is: "The age requirement for voting was enacted after the Civil War by the Fourteenth Amendment, setting the voting age at 21."
<h3>What is a credible source?</h3>
A credible source actually refers to the source that is reliable, trustworthy and true. It actually means a source which has firsthand information.
We see that the selected option is the sentence that that indicates that the source is not entirely credible because it's not clear what year the setting of voting age at 21 was ratified.
Learn more about credible source on brainly.com/question/784877
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