We have loaded a .csv file into a data frame called df. The first three columns are numeric, and when you run colnames(df) it returns "seconds" "humidity" "temperature" "vibration" "group" "type" "color" Given the code below, which answer will show the distribution of temperature?

Select one:

a. hist( temperature )

b. hist( df[2,] )

c. boxplot( df[ ,2] )

d. boxplot( df$temperature )