Multiple choice

Directions: Fill in the blank with the correct option.

________ the reactions of people with amnesia, scientists are learning about the process of memory of the brain.

  1. By studying

  2. To study

  3. They study

  4. They are studying
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

'By studying' is correct because after the preposition 'by', we use a gerund (-ing form). 'To study' is incorrect after 'by', and the other options ('They study', 'They are studying') create run-on sentences or don't fit grammatically.

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