In the following question, out of the four alternatives, select the alternative which will improve the bracketed part of the sentence. In case no improvement is needed, select "no improvement".
It must (being) quite an exciting time to be alive.
In the names Mangifera indica (mango), Solanum tuberosum (potato) and Panthera leo (lion), what does the three names, indica, tuberosum and leo, represent?
High-efficiency particulate air (HEPA), also known as high-efficiency particulate absorbing and high-efficiency particulate arrestance, is an efficiency standard of air filter.