Arrange the following words according to the dictionary.

1. Pestilential

2. Pesticide

3. Pestilence

4. Pestilent

5. Pestiferous

Given: 

1. Pestilential

2. Pesticide

3. Pestilence

4. Pestilent

5. Pestiferous

Pesticide comes first because it starts with "Pesti-" and the next letter "c" comes before "f," "l," or "t" in the other words.

Pestiferous comes next since "Pestif-" appears before "Pestil-".

Pestilence comes next, as "Pestil-" appears before "Pestilent" and "Pestilential".

Pestilent follows, as it is alphabetically before "Pestilential".

Pestilential comes last.

So, the correct order is: 2, 5, 3, 4, 1​
Pesticide, Pestiferous, Pestilence, Pestilent, Pestilential

Thus, correct option is (d).