Assertion : Holoblastic cleavage with almost equal-sized blastomeres is a characteristic of placental animals. Reason : Eggs of most mammals, including humans, are of centrolecithal type.

Step-by-step solution

In holoblastic cleavage, the cleavage furrows bisect the entire egg, or in other words, entire egg divides by each cleavage furrow. In placental mammals having isolecithal or microlecithal egg, the holoblastic cleavage produces blastomeres of equal or approximately equal size. Centrolecithal eggs are found in insects and in some hydrozoa. Here, yolk is concentrated at the centre of egg and the cytoplasm is present surrounding it. Meroblastic cleavage occurs in them.