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During the bleak winter months, when gardens lie dormant, and trees are bare, the vibrant green of houseplants can be a soothing balm for our spirits. Many people visit garden stores to reconnect with nature and breathe in the freshness that reminds them of spring.

With growing awareness about the harmful chemicals we introduce into our homes, like those from dry cleaning and various cleaners, there's an increasing need for plants that can improve indoor air quality. Many household products release chemicals such as formaldehyde, chlorine, and benzene, which can mimic allergy symptoms during winter when windows are shut. This reaction may stem from Multiple Chemical Sensitivity. Fortunately, research shows that certain houseplants can help filter these harmful substances, promoting a healthier living environment.
Ferns and palms are effective at removing chemicals from the air in homes. They release moisture during photosynthesis, drawing pollutants into their leaves. NASA has even found that palms can eliminate traces of formaldehyde quickly in controlled environments. Both plants are ancient, over a hundred million years old, and can live for 100 years or more. Their longevity and ability to grow tall (up to 65 feet) may enhance their environmental purifying qualities.

The passage indicates that research

Solution

✅ Correct Option: 1

Option 1: has only been conducted using specific plants.

The passage tells us that the research was carried out using certain selected plants — scientists picked particular types of plants to experiment with rather than testing every plant in the world.

Why the other options are wrong:

  • Option 2 → The passage does not limit the research to just NASA; other scientists may have also been involved.
  • Option 3 → The passage does not say that researchers failed to identify where the chemical impurities come from.
  • Option 4 → The research has benefits beyond just long-term space exploration — it can also help people on Earth, such as by improving indoor air quality.

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