John Anderson Uses Gas to Heat His Home

John Anderson uses gas to heat his home. He has accumulated the following information regarding his monthly gas bill and monthly heating degree-days. The heating degree-days value for a month is found by first subtracting the average temperature for each day from 65 degrees and then summing these daily amounts together for the month.
What will be the increase in John's monthly gas bill per heating degree-day using the high-low method?

A) $0.14
B) $6.59
C) $0.17
D) $5.77