Question

in the early stages the embryos are dropdown each other. as time progresses the embryos dropdown so the late embryos are dropdown each other. based on the anatomical features, the dropdown is least closely related to humans.

Explanation:

To solve this fill - in - the - blank question related to embryonic development and evolutionary relationships, we analyze the context:

Step 1: Analyze the first blank

In the early stages of embryonic development, different species' embryos are very similar to each other. This is a key concept in evolutionary biology, showing that early embryos of different organisms (including those related to humans and more distantly related ones) share many anatomical features. So the first blank should be filled with "most similar to".

Step 2: Analyze the second blank

As time (in the context of embryonic development) progresses, the embryos start to diverge in their anatomical features. They become more different from each other as they develop towards their respective adult forms. So the second blank is "become more different from".

Step 3: Analyze the third blank

We know that organisms that are more distantly related to humans will have embryos that diverge more from human embryos as development proceeds. For example, fish embryos diverge more from human embryos compared to, say, mammalian embryos. So the third blank (the organism whose embryo is least closely related to humans) could be a non - mammalian, non - primate organism like "fish" (or other distantly related organisms like reptiles, amphibians etc., but fish is a common example here).

Answer:

1. most similar to
2. become more different from
3. fish (or other distantly related organisms like reptile, amphibian etc.)