Final answer:
Option a) Prize; consequently, if you leave early, you automatically forfeit your potential winnings, is correct as it properly uses the semicolon before a transitional phrase introducing an independent clause.
Step-by-step explanation:
The best way to complete the text is: a) Prize; consequently, if you leave early, you automatically forfeit your potential winnings. This option correctly uses the semicolon to separate two closely related independent clauses.
The first clause ends with 'Prize,' and the second clause starts with 'consequently,' which is a transition word typically preceded by a semicolon when it leads into an independent clause.
Options b, c, and d are incorrect because they either incorrectly use the semicolon twice in a row, omit it completely, or misplace a comma.