How Much Does It Cost to Operate a 25-W Soldering $16 \phi$

Multiple Choice

How much does it cost to operate a 25-W soldering iron for 8.0 hours if energy costs 8.0¢/kWh?

A) $16 \phi$
B) $25 \phi$
C) $\$ 1.50$
D) $1.6 \phi$