Classification – Aquatic vs terrestrial flowers: three are commonly grown terrestrial garden flowers; one is primarily aquatic. Which option is the odd one out? Options: Rose, Lotus, Dahlia, Marigold.

Introduction / Context:
Plant classification can hinge on habitat. Most common garden ornamentals are terrestrial, but some iconic species are aquatic, which sets them apart.

Given Data / Assumptions:

• Rose: terrestrial shrub flower.
• Dahlia: terrestrial tuberous perennial.
• Marigold: terrestrial annual herb.
• Lotus: aquatic plant with floating leaves/flowers.

Concept / Approach:
Group flowers by primary habitat. The aquatic species stands out among terrestrial ones.

Step-by-Step Solution:
Identify Rose/Dahlia/Marigold → terrestrial culture.Identify Lotus → aquatic (ponds/water bodies).Therefore Lotus is the odd one out.

Verification / Alternative check:
Horticulture sources list lotus (Nelumbo) as an aquatic ornamental, unlike the others.

Why Other Options Are Wrong:
Rose/Dahlia/Marigold: All are typical garden flowers grown in soil beds.

Common Pitfalls:
Confusing lotus with water lily; both are aquatic, but either way the aquatic habitat remains the distinguishing factor.

Final Answer:
Lotus