What causes the mucus plug to break?

The correct answer will be- widening of the cervical canal to prepare itself for delivery of the child.

Explanation:

The mucus plug is the collection of the thick and acidic substance called mucus produced by the cervix during pregnancy period.  The mucus seals the cervical canal acting as a barrier to microorganism and unwanted infections to protect the uterus carrying a child.

The mucus plug breaks down when the cervical canal prepares itself for the delivery of the child. Thus, mucous breakdown acts as a precursor for the delivery of the child.

Thus, widening of the cervical canal to prepare itself for delivery of the child is the correct answer.

it has to be understood that the sea water contains a huge amount of sodium and chlorine ions and if they enter the cell of the atlantic cod fish, the cell will shrivel and the fish will die. to avoid such a condition, the fish uses active transport for the purpose of removing the ions against the gradient.

explanation:

the atlantic cod is not a maritime osmoconformer. its native application of salts is less than that of the seawater it lives in. it is continually falling water from the gills to the ocean via osmosis.

countering that, the fish is going to be swallowing seawater. but since its internal collection of salts is lower than seawater, the fish will want to go free of excess salt, and since that's going upon a gradient, then active transport, requiring energy, must be used to pump out the salt. much marine fish use the organs to filter out the salt and these fish discharge very straight urine.