Question: d.pizza is a data frame. It's a column named temperature contains only numbers. If you extract temperature using the [] accessors, its class defaults to numeric. How can you access temperature so that it retains the class of data.frame?
- `class( d.pizza( , "temperature" ) )`
- `class( d.pizza[ , "temperature" ] )`
- `class( d.pizza$temperature )`
- `class( d.pizza[ , "temperature", drop=F ] )`
Answer: The correct answer of the above question is Option D:`class( d.pizza[ , "temperature", drop=F ] )`