What does Lexicology, a brunch of linguistics study?

On what level is the word studied in its relationships with other words the vocabulary system?

1. 
   It is studied on the simple level.
   
2. 
   It is studied on the historical level.
   
3. 
   It is studied on the modern level.
   
4. 
   It is studied on the syntagmatic level.
   
5. 
   *lt is studied on the paradigmatic level.
   

5. 
   What is the smallest meaningful unit of speech?
   

1. 
   The smallest meaningful unit of speech is a stem.
   
2. 
   The smallest meaningful unit of speech is a word.
   
3. 
   The smallest meaningful unit of speech is a sound.
   
4. 
   *The smallest meaningful unit of speech is a morpheme.
   
5. 
   The smallest meaningful unit of speech is a root.
   

6. 
   Which words do we call homonyms?
   

1. 
   Homonyms are words which are identical in writing.
   
2. 
   Homonyms are the words which are identical in pronunciation.
   
3. 
   Homonyms are the words which are identical in speaking.
   
4. 
   * Homonyms are the words which are identical in sound and spelling.
   
5. 
   Homonyms are the words which are identical in their meaning.
   

7. 
   What is the leading semantic component in the semantic structure of the word?
   

1. 
   The leading component is termed connotative component.
   
2. 
   The leading component is called componential analysis.
   
3. 
   The leading component in the word is termed transformational component.
   
4. 
   *The leading component is termed denotative component.
   
5. 
   The leading component is called simple component.
   

8.