Answer: 43500
Step-by-step explanation
Circle or highlight the first three nonzero digits. That would be the 434.
Just after that is 7. The 7 fits the "5 or more" criteria, so we bump 434 up to 435. Everything afterward is replaced with 0s.
43472 rounds to 43500 when rounding to 3 sig figs.
The zeros in 43500 are not significant. If we wanted them to be significant, then we'd put a decimal point after the last zero.