Final answer:
The phrase "We were careful not to exchange more than the ordinary greetings" suggests caution.
Step-by-step explanation:
The phrase "We were careful not to exchange more than the ordinary greetings" suggests B. Caution. The context of the passage indicates that the speaker intentionally avoided engaging in deeper conversation, indicating a sense of wariness or caution in their interaction.
For example, the use of language such as "guarded advance" and the description of the rider's slow approach imply a sense of caution. Additionally, the gruff greeting and curt nod further emphasize the lack of warmth or friendliness in their interaction.