Answer:
1. The correct option is 4. Segment CB is congruent to segment AB.
2. The correct option is 3. The length of segment CD must be 6 cm.
3. The correct option is 3. The length of AC is 15.
Explanation:
Part 1:
From the given figure it is clear that AB=CB, AE=CE and AD=CD.
According the property of congruent segment, the equal sides and always congruent.
(Given)
Using property of congruent segment,

Segment CB is congruent to segment AB. Therefore the correct option is 4.
Part 2:
Measure of segment AD is 6 cm.


The length of segment CD must be 6, therefore the correct option is 3.
Part 3:
If point B is between points A and C, and AB = 6 and BC = 9, then



The length of AC is 15. Therefore the correct option is 3.