The correct option is (c) 1 and 3 only.
Explanation
Hens are oviparous animals that reproduce sexually. The process involves internal fertilization followed by the laying of eggs, which then undergo external development during an incubation period.- Statement 1 is Correct: Fertilization in hens is internal. The fusion of the male and female gametes takes place inside the female body, specifically in the oviduct, soon after the release of the ovum and before the formation of the protective layers.
- Statement 2 is Incorrect: The hard calcareous shell is formed around the developing embryo while it is still inside the hen's reproductive tract (specifically in the shell gland or uterus). The egg is laid with the hard shell already fully formed to protect the embryo during external development.
- Statement 3 is Correct: After the egg is laid, the embryo requires a specific temperature to develop, provided through incubation (either by the hen sitting on the eggs or artificially). The development period from laying to hatching for a chick is approximately 21 days (3 weeks).
Key Takeaway: In hens, fertilization is internal, but the development of the embryo occurs externally after the egg is laid. The hard shell is secreted internally before laying, and the incubation period is roughly 3 weeks.