[tex]\sf\frac{7.8\times 10^5~m}{1~hr} \times \frac{1~km}{1000~m} \times\frac{24~hr}{1~day}= \frac{(7.8\times 10^5) \times 24~km}{1000~day}\\\\= \frac{18720000~km}{1000~day}=18720 \frac{km}{day} = 1.872 \times 10^4 \frac{km}{day}[/tex]
Your answer is D
