In this comprehension question drawn from the passage on the TRAPPIST 1 exoplanet system, you must identify which factor made it easier for astronomers on Earth to record the dimming of starlight when the planets passed in front of their star.

Introduction / Context:
The passage about the TRAPPIST 1 system explains how astronomers detected the presence of seven Earth size planets by observing the dimming of their host star when the planets passed in front of it. This process is known as a transit. The author points out that certain properties of the star helped make these transits easier to detect from Earth. Specifically, the star is much cooler and smaller than our Sun, which affects how clearly the dimming of light can be recorded. The question asks you to choose the statement that best reflects this explanation from the passage.

Given Data / Assumptions:

• The passage states that the star around which these planets orbit is a dwarf star.
• It explicitly mentions that the dwarf star is much cooler than the Sun.
• Because of this property, the dimming of light during a transit is easier to record from Earth.
• The options offer different combinations of size and temperature in comparison with our Sun.
• We assume the reader knows that the correct option must match the phrasing in the passage.

Concept / Approach:
To solve this question, locate the part of the passage that talks about the recording of transits. The key phrase mentions that since the dwarf star is much cooler than the Sun, the dimming of light each time a planet passes in front of it can be easily recorded from Earth. A dwarf star is also generally smaller than a star like our Sun. One must choose the option that mentions both the smaller size and cooler temperature, because that combination aligns with the description in the text. Options that mention bigger or hotter stars contradict the passage and should be rejected.

Step-by-Step Solution:

Verification / Alternative check:
Verify your answer by comparing all listed alternatives with the contextual information. The passage never suggests that the star is bigger or hotter than our Sun. In fact, any option that describes a bigger or hotter star conflicts with the idea of a cool dwarf star. The only option that correctly brings together the idea of the star being smaller and cooler is option A. Additionally, there is no mention of a thick nebula around the star in the passage, so option E introduces information that is not present in the text and must be discarded. This cross checking confirms that option A is the only correct interpretation of the author explanation.

Why Other Options Are Wrong:
Option B suggests that the star is much bigger and cooler than our Sun, which contradicts the description of a dwarf star and does not appear in the passage. Option C describes the star as smaller and hotter than the Sun, mixing one correct concept with one incorrect property and therefore failing to match the text. Option D claims the star is much bigger and hotter, which is the opposite of what a dwarf star is and has no support in the passage. Option E introduces the idea of a thick nebula around the star, which is not mentioned at all and thus cannot explain why the transits were easier to record. Each of these alternatives either contradicts or adds information that is not in the passage.

Common Pitfalls:
Students sometimes assume that a brighter and hotter star would make observations easier because it emits more light, leading them to select options that mention bigger or hotter stars. This ignores the reasoning offered in the passage. Another pitfall is to overinterpret the term dwarf star and guess about size without reading the supporting sentence about temperature and observation. Some candidates also get distracted by additional scientific sounding phrases like thick nebula and pick an answer that seems elaborate rather than accurate. To avoid these mistakes, always base your answer solely on statements explicitly made in the passage and ignore any outside assumptions or extra details not mentioned in the text.

Final Answer:
The easier recording of the planetary transits was due to the fact that the star is much smaller and cooler than our Sun.