Question

read the passage and then answer the question.
in the early 1900s, a schoolteacher named wilhelm von osten captivated audiences in germany with the feats of his trained horse, hans. von osten claimed that hans could tell time, count objects, and even do basic arithmetic. when asked to find the sum of five and three, for instance, hans would provide the correct answer by tapping his hoof on the ground eight times. those who witnessed von ostens demonstrations began to extol hanss intelligence. they dubbed the horse clever hans and raved about his extraordinary mental reasoning abilities.
to determine whether hanss performance was simply a ruse, the german board of education sent a team of scientists to observe von osten and his horse. the team concluded that there were no tricks involved in the horses shows. however, oskar pfungst, a psychologist associated with the team, eventually realized that hans did not possess any mathematical acumen. instead, he was just picking up on subtle changes in peoples body language and using these cues to arrive at the correct number of taps. pfungst showed that people tend to make faint movements, such as tilting their heads slightly upward, when they expect to hear a certain answer. this propensity to provide unconscious behavioral clues has become known as the clever hans effect. scientists are now very careful to take this effect into consideration when designing experiments.
what is the meaning of propensity as used in the passage?
intention
preference
need
tendency

Explanation:

The passage states "people tend to make faint movements... This propensity to provide unconscious behavioral clues...". Here, "propensity" is used in the context of people having a certain way of acting (tending to make movements). "Tendency" means a likelihood to do something, which fits this context. "Intention" is about a plan or purpose, not relevant here. "Preference" is about liking one thing more than another. "Need" is about a requirement. So "tendency" is the correct meaning.

Answer:

tendency