Question 20 - Reading and Writing Practice Test for the SAT Exam

When mechanical clocks began to appear in European cities during the late 13th century, they were initially met with skepticism. Many local guilds, especially those related to manual timekeeping methods, opposed the technology because they believed ____ to be a threat to traditional practices and their livelihoods.

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