`IUPAC` name of given compound is:
`H-undersetunderset(O)(||)(C)-CH_(2)-undersetunderset(CH_(3))(|)(CH)-C=N`

Options

A. `3`-Carbonitrile-`3`-methyl butanal
B. `3`-Formyl-`2`-methyl propane nitrile
C. `3`-Cyanobutanal
D. `2`-Methyl-`4`-formylbutane nitrile

Answer

To determine the IUPAC name of the given compound, we will follow these steps:

### Step 1: Identify the Functional Groups
The compound has two functional groups:
- An aldehyde group (–CHO)
- A nitrile group (–C≡N)

### Step 2: Determine the Priority of Functional Groups
According to IUPAC nomenclature rules, the nitrile group (C≡N) has a higher priority than the aldehyde group (–CHO). Therefore, the nitrile group will be treated as the suffix, while the aldehyde group will be treated as a substituent.

### Step 3: Count the Carbon Atoms
We need to count the total number of carbon atoms in the longest continuous chain that includes the nitrile group. The structure indicates that there are 4 carbon atoms in total.

### Step 4: Name the Parent Chain
Since there are 4 carbon atoms in the longest chain, the parent hydrocarbon is "butane." Because the nitrile group is present, we will use the suffix "nitrile," leading to "butanenitrile."

### Step 5: Identify and Name the Substituents
- There is a methyl group (–CH₃) attached to the second carbon.
- There is a formyl group (–CHO) attached to the fourth carbon.

### Step 6: Assign Locants to the Substituents
We need to assign locants to the substituents based on the numbering of the parent chain:
- The methyl group is at position 2.
- The formyl group is at position 4.

### Step 7: Combine the Names
We will combine the names of the substituents with the parent chain name. The correct order is to list the substituents in alphabetical order:
- Methyl (2-methyl)
- Formyl (4-formyl)

Thus, the IUPAC name of the compound is:
**2-methyl-4-formylbutanenitrile**

### Final Answer
The IUPAC name of the given compound is **2-methyl-4-formylbutanenitrile**.

---