Correct Answer: limited

Solution : The correct choice is the second option.

Explanation:
The correct option to fill in the blank is limited. The sentence suggests that the watch is expensive because it belongs to a limited edition, indicating that only a restricted number of such watches were produced. Limited-edition items are often considered more valuable and exclusive, contributing to their higher price.
The meanings of the other options are as follows:

• Outdated: No longer in fashion or no longer current.
• Old: Having existed for a long time; not new.
• Formal: Conforming to established customs or rules; suitable for official or ceremonial occasions.

Therefore, the complete sentence would be: This watch is expensive as it is a limited edition watch.