During which geologic epoch do scientists infer
that the earliest grasses first appeared on earth?
(1) holocene
(2) pleistocene
(3) oligocene
(4) eocene

The correct answers is Eocene. Scientists infer that the earliest grasses on Earth first appeared during the Eocene epoch, a part of the Tertiary period. Along with the growth of grasses are herbivores that thrive and some mammals like camels, horses, and rodents. 

The color would be Pink

Explanation:

According to the question, the bacteria is positive for the enzyme urease and it's inoculated for 24 hours.

Urease broth is a differential medium that tests the ability of an organism to produce urease, that hydrolyzes urea to ammonia and carbon dioxide. The broth contains two pH buffers, urea, a very small amount of nutrients for the bacteria, and the pH indicator phenol red. Phenol red turns yellow in an acidic environment and fuchsia in an alkaline environment.

If the urea in the broth is degraded and ammonia is produced, an alkaline environment is created, and the media turns pink within 24 hours.

Many enterics can hydrolyze urea; but only a few can degrade urea rapidly. These are called “rapid urease-positive” organisms.

Urea broth is formulated to test for rapid urease-positive organisms. The restrictive amount of nutrients coupled with the use of pH buffers prevent all but rapid urease-positive organisms from producing enough ammonia to turn the phenol red pink.