Take a look at the attachment below. It fills in for the attachment that wasn't provided in the question -
An oblique pyramid is one that has a top not aligned with the base. Due to this, the height of the pyramid connects with two vertices at its ends to form a right angle present outside the pyramid, knowing that it is always perpendicular to the base. There is no difference between the calculations of the volume of an oblique pyramid and a pyramid however -
<u><em>And thus, you're solution is 5 cm^3, or in other words option b!</em></u>
