Sounds like someone chose the wrong compound to give students as homework!
There are two groups of chemically equivalent protons, of course. One at 3.7ppm and one at 1.8ppm, but because there is no free rotation around any of the C-C or C-O bonds, they are not magnetically equivalent. In the first order approximation (vicinal couplings only), the group at 3.7 ppm can have up to 16 peaks and the group at 1.8 ppm can have up to 64 peaks (in reality there's probably half of that due to symmetry, but if you count four-bond couplings, which can easily be over 1Hz here, then there's a lot more peaks to find). Everybody's favorite public database AIST SDBS doesn't have a well-resolved spectrum of THF, but in their 2-methyl THF, the 1.8ppm multiplet has 52 visible peaks!
Only (D) is a simple question :) two signals, one at 68ppm, one at 26ppm.