Answer:
LP ⊥ PN
Explanation:
Given



See attachment
Required
What proves LMNP is a rectangle
The additional information needed is LP ⊥ PN
Because:

This can be true for other shapes, such as trapezoid, etc.

The slopes of LP and MN will be the same because both sides are parallel; However, this is not peculiar to rectangles alone. Same as option (c)
(d) LP ⊥ PN
This must be true i.e. LP must be perpendicular to PN