Answer: Second diagram and fourth diagram.
Explanation:
A kite is a quadrilateral which has two pairs of congruent adjacent sides.
In diagram 1:
By the distance formula,
The sides of the given quadrilateral are
,
,
and

Since, here a, b, c and d are unknown numbers,
Thus, this quadrilateral does not have any pair of congruent adjacent sides.
⇒ It is not a kite.
In diagram 2:
By the distance formula,
The sides of the given quadrilateral are
,
,
and

Since, this quadrilateral has two pairs of congruent adjacent sides.
⇒ It is a kite.
In diagram 3:
By the distance formula,
The sides of the given quadrilateral are
,
,
and

Since, here a, b, c and d are unknown numbers,
Thus, this quadrilateral only have only one pair of congruent adjacent sides.
⇒ It is not a kite.
In diagram 4:
By the distance formula,
The sides of the given quadrilateral are
,
,
and

Since, this quadrilateral has two pairs of congruent adjacent sides.
⇒ It is a kite.