Multiple choice The structure of auxin was first determined by _______________________. David Rockwell Goddard Kenneth Vivian Thimann Ernst Munch Georges Ville Jose R. Velasco Reveal answer Fill a bubble to check yourself B Correct answer Explanation Kenneth Vivian Thimann is known for his studies of plant hormones, which were widely influential in agriculture and horticulture. He isolated and determined the structure of auxin, the first known plant hormone.