Q68

Consider the following relation schemas : b-Schema = (b-name, b-city, assets) a-Schema = (a-num, b-name, bal) d-Schema = (c-name, a-number) Let branch, account and depositor be respectively instances of the above schemas. Assume that account and depositor relations are much bigger than the branch relation. Consider the following query: Пc-name (σb-city = "Agra" ⋀ bal < 0 (branch ⋈ (account ⋈ depositor) Which one of the following queries is the most efficient version of the above query ?