[单选题]
The Leaning Tower of Pisa is 55 mzbpqz (pgta. 0n+)q. z tall and about j4fn(z/mv d+ o+o u**ror5mrc7.0 m in diameter. The top is 4.5 m off center. How much farther can it o5nr4+mv *(+ucfdojr /mrz*olean before it becomes unstable?
A. $0.5 \; m$
B. $1.5 \; m$
C. $2.5 \; m$
D. $3.5 \; m$