SAT Mock Test 3
Complete both sections to finish the test.
Reading Passage:
The following is from a text about the Cambrian Explosion. The Cambrian Explosion, which occurred approximately 541 million years ago, marks one of the most dramatic and puzzling episodes in the history of life. Over a relatively short period of geological time, there was a sudden and extraordinary diversification of animal life. Many of the major animal phyla that exist today first appeared in the fossil record during this period. The causes of this rapid evolution are still debated by scientists, with hypotheses ranging from environmental changes, such as an increase in oceanic oxygen, to developmental innovations in animal genetics.
Question 1: What is the main topic of the passage?
Question 2: Which choice completes the text with the most logical and precise word or phrase? The politician's speech was filled with platitudes and vague promises, but it lacked any ______ proposals for addressing the city's problems.