Correct Answer - D
After arriving at the wall of the ovary, the pollen tube enters the ovule either through the micropyle or by some other route. The entrance of the pollen tube through the micropyle is the normal condition and is known as porogamy. In some cases the pollen tube enters the ovule through the chalaza (chalazogamy e.g. Casuarina), or through integuments (mesogamy e.g. Cucurbita).
