Arrange the given words in the sequence in which they occur in the dictionary.

1. radiance

2. rainbow

3. radical

4. radiology

5. railing

13452

The option that represents the correct order of the given words as they would appear in an English dictionary is shown below:

1. radiance

3. radical

4. radiology

5. railing

2. rainbow

 Hence, '13452' is the correct answer.