Explanation:

- The phrase "Where there is a will, there is a way" is a well-known proverb. It means if someone is determined to do something, they will find a way to achieve it despite obstacles.

- Let's break down the options:

- Option 1: willing

- Means being ready, eager, or prepared to do something.

- Does not fit the phrase structure.

- Option 2: wills

- Third person singular form of the verb "to will."

- Does not fit the phrase structure.

- Option 3: willed

- Past tense of the verb "to will."

- Inappropriate for this phrase.

- Option 4: will

- Refers to determination or intent.

- Correct completion of the phrase: "Where there is a will, there is a way."

The correct word to fill in the blank is Option 4: will. .