Since dogs may be attracted to alcoholic beverages left out by the motel guests, it is strongly recommended to keep drinks and bottles out of their reach at all times.

(a) it is strongly recommended to keep drinks and bottles out of their
(b) it is highly recommended that drinks and bottles be kept out of dogs'
(c) it strongly recommended to keep drinks and bottles out of dogs'
(d) it is highly recommended that drinks and bottles are kept out of dogs'
(e) it is highly recommended to keep drinks and bottles out of dogs'

OA E

Source: Economist Gmat