`P Q R S` is a quadrilateral. `P R\ a n d\ Q S` intersect each other `Odot` In which of the following cases, `P Q R S` is a parallelogram? (a) `/_P=100^0,\ /_Q=80^0,\ /_R=100^0` (b) `/_P=85^0,\ /_Q=85^0,\ /_R=95^0` (c) `P Q=7C M ,\ Q R=7C M ,\ R S=8C M ,\ S P=8C M` (d) `O P=6. 5 c m ,\ O Q=6. 5 c m ,\ O R=5. 2 c m ,\ O S=5. 2 c m ,`

Explanation

To determine in which case the quadrilateral PQRS is a parallelogram, we will analyze each case using the properties of quadrilaterals.

### Step-by-Step Solution:

**Step 1: Understand the properties of a parallelogram.**
A quadrilateral is a parallelogram if:
1. Opposite sides are equal.
2. Opposite angles are equal.
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