Why are neanderthals considered a different species?

Neanderthals are considered a different species because while some Homo sapiens interbred with Neanderthals, the numbers were few. Also, the crossbreed is very different and far off. It's like saying you'll cross a dolphin and a monkey to get a donkey, which doesn't work or make sense. 

This is what i found on google“ the monomers combine with each other via covalent bonds to form larger molecules known as polymers. in doing so, monomers release water molecules as byproducts. this type of reaction is known as dehydration synthesis, which means “to put together while losing water. in the process, a water molecule is formed.” i hope this you

The correct answer is d