___________ you take a taxi, you will still miss your plane. The mostappropriate transitional device to fill in the blank will be

The most appropriate transitional device to fill in the blank would be "Even if."

Using this phrase establishes a conditional relationship, emphasizing that regardless of the action taken (taking a taxi), the outcome (missing the plane) remains unchanged. This transition effectively communicates that the action will not alter the inevitability of the outcome, which is critical in conveying the message clearly.

In this context, other options could include "Although" or "Whether," but they do not convey the same level of certainty about the outcome as "Even if" does. Therefore, "Even if" is the best choice for this sentence.