Question

To train a puppy, first buy some small dog biscuits or other small dog treats. (2) Then teach the puppy one short command, such as "Sit!"—speaking the word loudly and firmly until he or she obeys. (3) _____ you get a correct response, give the dog a treat and praise him or her loudly.
a. then

b. soon

c. first

d. also

Answer 1

Its A.then for your question....

Answer 2

Then. 

Hope it helped! :)