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Verbal·Standard English Conventions·Within-Sentence Punctuation
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2026-07-29T22:44:53.591471 image/svg+xml Matplotlib v3.10.9, https://matplotlib.org/
Source: NASA “Current and Past Missions”

Scientists have been launching cometary missions
since 1978. The first one, a joint mission by the European
Space Agency and the National Aeronautics and Space
Administration (NASA), was a “flyby” in which the
spacecraft collected data while passing around Comet
Giacobini-Zinner. 1 The landing of the Rosetta space
probe on comet 67P/Churyumov-Gerasimenko in 2014
marked the first time that a probe landed directly on a
2 comet and giving scientists an unprecedented
opportunity to study the surface of a comet. In order to
continue this valuable research, additional missions are
needed; thus, it is critical that more funding be allocated
for this purpose.

The 2014 Rosetta mission provided a rare opportunity
for scientists to test a number of hypotheses regarding
the composition of 3 comets; the distribution of organic
compounds in our solar system and the origins of life
on Earth. Unlike other cometary missions, the Rosetta
spacecraft contained a probe, Philae, that was able to land
on the surface of a comet. Based on data collected from
Philae, scientists were able to conclude that the water vapor
on the comet was substantially different than the water
vapor on Earth, suggesting that the water on Earth likely
did not originate from comets. In addition, scientists have
used the data from Philae 4 to investigate why essential
amino acids on Earth exist almost exclusively in one of two
possible forms. Claudia Alexander, a project scientist for
Rosetta at NASA’s Jet Propulsion Laboratory, says that the
data collected from 67P will give us a fuller understanding
of how substances form to create livable environments.

In addition to improving our understanding of life on
Earth, an increase in funds for cometary missions would
give scientists an opportunity to learn from 5 they’re
failures and improve future missions. During the Rosetta
mission, for example, the probe bounced and did not
fully insert itself into the comet. Luckily, the landing did
succeed, but more opportunities for trials would help
scientists perfect their methods and aid in the collection of
data from different types of comets in our solar system.
Which choice is the best version of the underlined portion? If the original is best, choose NO CHANGE.
A
NO CHANGE
B
to investigate, why
C
to: investigate why
D
to investigate why: