We spend () of time studying vocabulary.

• A. A good deal
• B. A little
• C. Some
• D. Many

Answer: (A)

We spend a good deal of time studying vocabulary means we devote a large amount of time to it. The phrase “a good deal of time” is a natural, common way to say a lot of time, and it fits with the uncountable noun time after spend. The other options don’t fit this sentence structure: a little time would work in a different construction (without “of”), some time or some of time isn’t the natural pairing with “of time” here, and many is used with countable nouns, not uncountable time. So the best choice expresses a large amount of time.