They seem to feel that the danger of the traffic is (27) ___________ to the risk of having their conversation be overheard.

Knowledge of type words:

A. preferable /ˈprefərəbəl/ (a): better

B. prefer /prɪˈfɜːr/ (v): like

C. preference /ˈprefərəns/ (n): preference, preference

D. preference /prefərˈenʃəl/ (a): preference

After the verb to be we need an adjective. From there, we eliminate B, C

They seem to feel that the danger of the traffic is (27)_______ to the risk of having their conversation be overheard.

They seem to feel that the danger of traffic is better than the risk of their conversation being overheard.