Ignoring the question of SUSPICION vs. SUSPICIONS for a moment, both have the same error, and should read: "The customer's behavior arousearousedTHE suspicion/suspicions of the shopkeeper." The sentence is written in past tense, so you need AROUSED not AROUSE, and you need the definite article with either SUSPICION or SUSPICIONS. The question would be better
After further consideration, I think "The customer's behavior aroused the suspicion (singular) of the shopkeeper" is probably better. Neither option is wrong though.
ATTENTION is similar to SUSPICION in this respect, but different in that the word ATTENTIONS has a specific meaning: "nice things you do for someone", as in "She loved him, and lavished her ATTENTIONS on him whenever t