## Question 1
What is the lowest common ancestor of $8$ and $6$ in the following binary tree?
```text
  5
 / \
6   7
   / \
  8   9
```
### Options

1. 5
Correct
$5$ is the lowest common ancestor of $8$ and $6$.
----------------------------

2. 6
Incorrect

----------------------------

3. 7
Incorrect

----------------------------

4. 8
Incorrect

----------------------------

---------------------------------------------

## Question 2
What is the lowest common ancestor of $9$ and $3$ in the following binary tree?
```text
     6 
   /   \
  9     4
 /       \
3         8
```
### Options

1. 6
Incorrect

----------------------------

2. 3
Incorrect

----------------------------

3. 9
Correct
Because a node is a descendant of itself, the lowest common ancestor of $9$ and $3$ is $9$.
----------------------------

4. 4
Incorrect

----------------------------

---------------------------------------------

## Question 3
What is the lowest common ancestor of $4$ and $7$ in the following binary tree?
```text
     5 
   /   \
  2     3
 /       \
4         7
```
### Options

1. 4
Incorrect

----------------------------

2. 3
Incorrect

----------------------------

3. 2
Incorrect

----------------------------

4. 5
Correct
The lowest common ancestor of $4$ and $7$ is the root node, $5$.
----------------------------

---------------------------------------------