Long after being bitten by a stray dog, alonzo found that his fear of dogs seemed to have disappeared. to his surprise, however, when he was recently confronted by a stray dog, he experienced a sudden twinge of anxiety. this sudden anxiety best illustrates:
a. delayed reinforcement.
b. latent learning.
c. spontaneous recovery.
d. shaping.
e. discrimination.

Spontaneous recovery

Explanation:

Spontaneous recovery is the phenomenon of learning and conditioning. Spontaneous recovery as the name indicated it is the reappearance of the response. It has been occur-ed when a person not exposed to the conditioned stimulus. It is called spontaneous recovery because in it the response occurs instantly from out of nowhere.  

Thus here in the above statement, as Alonzo has been bitten a stray dog a long time before, he seemed fearless but recently again e was confronted by a stray dog, he gets twinge again from anxiety due to spontaneous recovery of the conditioned stimulus,  

productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.