Decrease (-I) effect of given is:

I. CN
II. NO₂
III. NH₂
IV. F

A. II > I > IV > III
B. II > III > IV > I
C. III > II > IV > I
D. III > II > I > IV

To solve the question regarding the decreasing order of the \(-I\) (negative inductive) effect of the given groups, we first need to understand the \(-I\) effect of each group:

1. **CN (Cyanide group)**: The cyano group is a strong electron-withdrawing group due to its electronegativity and the presence of a triple bond between carbon and nitrogen. It has a significant \(-I\) effect.

2. **NO2 (Nitro group)**: The nitro group is also a strong electron-withdrawing group. It pulls electrons away from the attached carbon or other atoms due to resonance and its electronegative oxygen atoms. Its \(-I\) effect is significant but slightly less than that of the cyanide group.

3. **NH2 (Amino group)**: The amino group has a +I effect due to its ability to donate electron density. However, it can exhibit a slight \(-I\) effect under certain conditions, but it is generally weaker compared to the other groups mentioned.

4. **F (Fluorine)**: Fluorine is highly electronegative and has a strong \(-I\) effect due to its high electronegativity. However, it has a weaker effect than the cyano and nitro groups because of its +I effect through its lone pairs.

Now, let's rank them based on their \(-I\) effects:

- **CN > NO2**: Cyanide has a stronger \(-I\) effect than the nitro group.
- **NO2 > F**: The nitro group has a stronger \(-I\) effect than fluorine.
- **F > NH2**: Fluorine has a stronger \(-I\) effect than the amino group, which has a +I effect.

So, the order of decreasing \(-I\) effect is:

**CN > NO2 > F > NH2**

In terms of the options provided, this corresponds to option **A: II > I > IV > III**.

### Final Answer:
A. II > I > IV > III