Heat transfer in liquids and gases primarily occurs by which method?

Heat transfer in different states of matter follows different dominant mechanisms. Option A (Conduction) is incorrect — while conduction can occur in liquids and gases, the image specifically states that conduction of heat in liquids and gases by this method is very poor (द्रवों व गैसों में ऊष्मा का संचरण इस विधि द्वारा बहुत कम होता है). This is because in liquids and gases, molecules are not tightly packed like in solids, making direct particle-to-particle vibration transfer inefficient. Option B (Convection) is CORRECT — heat in liquids and gases primarily transfers by convection. The image states: गैसों व द्रवों में ऊष्मा का संचरण किस विधि द्वारा होता है — संवहन विधि (Convection) द्वारा. Option C (Radiation) is incorrect — radiation can occur through liquids and gases, but it is not the primary mechanism of heat transfer in fluids. Radiation is the primary mechanism in vacuum or when no medium is present. Option D (All three equally) is incorrect — the three modes are not equally dominant in liquids and gases. Convection is overwhelmingly dominant in fluids.