(a) The nectar present in the flowers of plants serves as food for bees. Bees suck nectar from flowers.
(b) Humans obtain honey made by bees and consume it as food.
(c) This food chain differs from an usual one, as humans, here, consume honey made by bees, whereas, usually, the food chain resembles Plants Goats Humans, in which humans consume the meat of goats directly.
(d) No, it cannot be regarded as a food chain, as humans do not consume bees directly but only consume the food made by them.