In the 1970s, Janaki Ammal, a prominent botanist, emerged as a powerful voice in India's environmental conservation movement. Her exhaustive chromosomal survey of plants in Silent Valley, a pristine tropical forest in Kerala, India, that is home to nearly 1,000 species of native flora (many of which are endangered), ________ instrumental in the government's decision to preserve the forest.

Which choice completes the text so that it conforms to the conventions of Standard English?