Which word does not suggest use of the mind?

a. improvise

b. ostentation

c. speculate

d. visionary

First, we will define each. Improvise is the impromptu do of things. Ostentation is the exaggerated display of knowledge to attract affirmation from others. Speculate is to make guesses without prior evidence. Visionary is trying to foresee the future and making plans about it. Out of the 4, speculate does not utilize the logical/rational/left side of the brain. It uses the gut feeling, to decide and give opinion on things and events. This is different from improvise as it needs quick thinking and the ability to think with inititative.