Final answer:
The correct sentence is option A: At fifteen, Washington became a surveyor; his first job was to survey the six-million-acre estate of his neighbor Lord Fairfax.
Step-by-step explanation:
The corrected sentence is: A. At fifteen, Washington became a surveyor; his first job was to survey the six-million-acre estate of his neighbor Lord Fairfax. This option uses a semicolon to appropriately separate the clauses, making the sentence clear and grammatically correct. It ensures proper punctuation and maintains the logical flow of information. The semicolon indicates a stronger connection between the two related clauses than a comma alone would provide.