The Amount of Time Single Men and Women Spend on House

The amount of time single men and women spend on house work is measured for 15 single women and 25 single men. For the women the mean was 7 hours/week with a standard deviation of 1.5. For the men the mean was 4.5 hours/week with a standard deviation of 1.1. What is the value of the pooled standard deviation for the difference in mean time spent on housework between single men and women?

A) 1.30
B) 0.45
C) 1.59
D) 1.26