Question

Eggs of placental mammals are

• A. Microlecithal
• B. Mesolecithal
  
• C. Alecithal
• D. Homolecithal

Answer 1

The correct option is C Alecithal

Homolecithal
Homolecithal is the egg in which yolk is evenly distributed within the egg. Examples include sea urchin eggs.

Alecithal
Eggs with no yolk are called alecithal eggs. Examples include human eggs.
Yolk provides necessary nutrition to the developing embryo. But in placental mammals the embryo is connected to the mother through the placenta which facilitates the supply of oxygen and nutrients to the embryo.

Microlecithal
Eggs contain very little yolk in it but the amount of cytoplasm is high. Examples include amphioxus egg

Mesolecithal
Eggs with a moderate amount of yolk are called mesolecithal eggs. Examples include amphibians, $Petromyzon$ etc.

Final answer
(B) Alecithal