Which of the following is an example of variation? A)A wolf species that has different lengths of fur
B)A frog that has changed over time to hop faster
C)A lake that has become more clear with new environmental protection

☆ionisation energy increases across a period from na -> ar☆ionisation energy decreases down a group from li -> fr☆ionic radius decreases across a period from na -> cl☆ionic radius increases down a groupfrom f -> ii hope it clarifies your doubts