The correct option is crocodile.

To understand why this is the correct answer, we can analyze the idiom referenced in the sentence: "He always sheds tears to deceive people."
This sentence describes someone who pretends to show sadness, grief, or sympathy in order to deceive or manipulate others.

This behavior is directly associated with the famous English idiom "crocodile tears."
The phrase comes from an ancient belief or myth that crocodiles shed tears while consuming their prey, or to lure their victims. Thus, shedding "crocodile tears" means showing insincere, hypocritical, or false sorrow.

Let's look at the structure of the sentence to see how the word fits grammatically:
"He is known for his unscrupulous ways. He always sheds __________ tears to deceive people."
By inserting the word "crocodile" into the blank, we complete the standard idiomatic expression: "crocodile tears."

Therefore, the option "crocodile" is the correct choice to complete the description of his deceitful behavior.