The IUPAC name of
`{:OHC-CH=CH-underset(" "CH_(2)CH_(2)CH_(2)CH_(3))underset(|" ")(CH)-CH=CH_2:}`

Options

A. 5-Vinyloct-3-en-1-al
B. 4-Butyl-2, 5-hexadien-1-al
C. 5-Vinyloct-5-en-8-al
D. 3-Butyl-1, 4-hexandien-8-al

Explanation

To determine the IUPAC name of the given compound, we will follow a systematic approach. Here’s a step-by-step breakdown of the solution:

### Step 1: Identify the Longest Carbon Chain
First, we need to identify the longest continuous carbon chain in the compound. In this case, we have two potential chains:
- One chain consists of 6 carbon atoms.
- The other chain consists of 8 carbon atoms.

**Hint:** Look for the longest chain that includes the functional groups and double bonds.

### Step 2: Choose the Parent Chain
Since the chain with 8 carbon atoms has a double bond, we will select the 8-carbon chain as the parent chain. This is because we prioritize chains with functional groups over simple alkyl chains.

**Hint:** Always prioritize chains with functional groups when determining the parent chain.

### Step 3: Identify Functional Groups and Substituents
In the selected parent chain, we have:
- An aldehyde functional group (–CHO).
- A butyl substituent (a 4-carbon alkyl group).

**Hint:** Identify all functional groups and substituents attached to the parent chain.

### Step 4: Number the Parent Chain
We will number the carbon atoms in the parent chain starting from the end closest to the functional group to give it the lowest possible number. The numbering will be as follows:
1. The aldehyde group gets the number 1.
2. The double bonds will be numbered next.

**Hint:** Use the lowest locants rule to assign numbers to functional groups and double bonds.

### Step 5: Determine the Parent Name
The parent chain has 6 carbon atoms, which corresponds to "hexane". Since there are two double bonds, we will use the suffix "diene". Therefore, the base name is "hexadiene".

**Hint:** Remember to modify the base name according to the number of double bonds present.

### Step 6: Combine the Suffixes
Since we have two double bonds, we will write "hexadiene". The locants for the double bonds are 2 and 5. Therefore, we write it as "2,5-hexadiene".

**Hint:** Use commas to separate locants and hyphens to connect them to the base name.

### Step 7: Add the Functional Group Suffix
The aldehyde functional group is indicated with the suffix "al". Since the double bond and the aldehyde are both present, we will combine them. The final part will be "1-al".

**Hint:** When combining suffixes, drop the 'e' from "hexadiene" to avoid vowel clashes.

### Step 8: Include the Substituent
The butyl substituent is located at carbon 4. Therefore, we add "4-butyl" before the parent name.

**Hint:** Always specify the position of substituents relative to the parent chain.

### Final IUPAC Name
Putting it all together, we have:
**4-butyl-2,5-hexadiene-1-al**

### Conclusion
The IUPAC name of the compound is **4-butyl-2,5-hexadiene-1-al**.