The answer is A
Mucus protects the stomach lining from digestive secretions
Yes they did. It is generally known that amphibians breathe through their skin.
The outer planets are mostly formed of lighter elements because these three condense are a<u> lower temperature</u>.
<u>Explanation:</u>
The planets based on the location of the sun is divided into two, that is outer planets and inner planets.
The Outer planet which is far from the sun consists of larger quantity of lighter substances such helium, hydrogen, methane which would condense at the lower temperature. And remains gaseous inside the frost line that would exit far away for the sun so the temperature is low and the lighter materials are easier to condense in lower temperature to form terrestrial rocks.
Material through which water flows is permeable. This material can be either natural or artificial. Naturally permeable material can be clean sand and gravel for example, or a sandstone and in the latter case the sandstone can have both porosity which is not synonymous with permeability as the pores must be connected to be permeable. An impermeable membrane could be used to line ditches for example to prevent leakage near mines.
