Improve the bracketed part of the sentence.
Scientists (have developed) an “organ-on-a-chip” platform to study how drugs are transported across the human placental barrier.
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. No improvement.
- A plural subject needs a plural verb.
- After 'have/has/had', only the third form of the verb is used.
- The sentence already fulfils the above conditions.
Hence, the chosen option is correct.