Which definition is the correct usage of the word “alternate” in the following sentence?

To give the garden a nice variety, I alternate the types of flowers I plant each year.

to change back and forth between conditions; to take turns

every second one or every other of a series

constituting an additional or different option

a person who fulfills the duties of one who is absent

Question

Which definition is the correct usage of the word “alternate” in the following sentence?

To give the garden a nice variety, I alternate the types of flowers I plant each year.
 
to change back and forth between conditions; to take turns 

every second one or every other of a series 

constituting an additional or different option 

a person who fulfills the duties of one who is absent

anonymous · Answer

to change back and forth between conditions; to take turns

anonymous · Answer

Thank you so much!! Do you mind helping me with a few more?

anonymous · Answer

sure, i'll try my best