Explanation:

- Her ______ of smell is wonderful.

- This sentence describes the ability someone has to perceive smells.

- Option 1: sacks

- "Sacks" refers to bags or pouches and is unrelated to the ability to smell.

- Option 2: sense

- "Sense of smell" is a common expression referring to the ability to recognize and distinguish different odors.

- Correct Answer: The most fitting word here is "sense."

- Option 3: science

- While science explores topics like smell, it isn't about the ability to smell directly.

- Option 4: census

- "Census" is a systematic counting of a population, unrelated to smell.