Answer:
1st answer: a.(2,1)
2nd answer: b. 9 ft, 12 ft, 15 ft
3rd answer: a.
Explanation:
For 1st Question;
To make a congruent triangle, it must fulfill ASA, SSS, SAS,etc. axiom.
When we plot D(2,1) we get,
AB=DC=4.1
BC=AD= 4
AC= AC
Since, ABC≅ACD by SSS axiom.
For more detail: See attachment
Therefore, answer is a.(2,1)

For 2nd Question:
To make a similar triangle the corresponding side should be proportional.
let's check a.
3/8=3/8
4/11=4/11
Since the side are not proportional so they are not similar triangle.
Let's check b.
3/9=1/3
4/12=1/3
5/15=1/3
Since the side are proportional so they are similar triangle.
Therefore, the answer is b. 9 ft, 12 ft, 15 ft

For 3rd Question:
To make a similar triangle the corresponding angle should be equal.
let's check a.
∡D=∡C Given
They are equal means that AD ║ BC.
∡A=∡B alternate interior angle
And remaining angle will be automatically equal as a remaining angle of a triangle. By AA postulate
So, option a. contains a pair of similar triangle,