Digital to Analog Converter math question
Technically, 0V is the maximum output and -8.25 would be the lowest

LSB voltage is -5*Rx/300000

4 bits would be Vout = -5*15*Rx/300000

Solving for Rx yields 33K which still isn't in the list of answer, so it looks like 37.5K is the closest which would produce down to -9.375