A man has to plant exactly four varieties of flowers in a flower bed in his garden, one variety in each of the four rows, in an ascending order of height from the first row to the fourth row. The seven varieties available to the man, in ascending order of height, are red begonias (RB), pink petunias (PP), orange marigolds (OM), red geraniums (RG), white snapdragons (WS), yellow zinnias (YZ) and pink cosmos (PC). The following restrictions on color arrangements apply: No two varieties of the same color can be planted. Orange flowers cannot be planted in a row immediately adjacent to a row of yellow flowers. If the man plants the begonias and the petunias, then which of the following must also be planted?

Explanation: (C) Begonias (RB) and Petunias (PP) are the two shortest flowers. Because of the ascending order, they must be placed in **Row 1 (RB)** and **Row 2 (PP)**. We need 2 more flowers for Row 3 and Row 4. Remaining varieties: {OM, RG, WS, YZ, PC}. The arrangement so far: RB, PP, Row 3, Row 4. (1) No same color: RB is Red, PP is Pink. So, RG (Red) and PC (Pink) are excluded. Remaining varieties: {OM, WS, YZ}. We need 2 flowers from this set. All are in ascending height order and taller than PP: OM < WS < YZ. The only pair that fits Row 3 and Row 4 is **WS** and **YZ**. (WS and YZ in any order is not allowed, so it must be WS in Row 3 and YZ in Row 4). (2) OM not adjacent to YZ: OM is not in the set {RB, PP, WS, YZ}. OK. The flowers must be planted are {RB, PP, WS, YZ}. Thus, the Snapdragons (WS) and Zinnias (YZ) must also be planted. Snapdragons is the third item that must be planted. Zinnias is the fourth item. Since Zinnias is an option and Snapdragons is an option, we select Snapdragons as it is the first choice to fill the required spot. The answer choice is C (The snapdragons) based on the requirement of one *must also be planted*.