What does it mean for a membrane to be selectively permeable?

only certain molecules are allowed to pass through.

the membrane is rigid and only allows water to pass through.

all types of molecules are able to pass into the cell.

the membrane is rigid and nothing can enter or leave the cell.

Answer;

Semi-permeability means that only certain molecules are allowed to pass through.

Explanation;

-Semi-permeability is one of the features of a cell membrane, which means that the membrane allows selective movement of materials in and out of the cell; that is only certain molecules can enter or leave the cell.

-For example smaller molecules such water and ions such as potassium and sodium ions are able to leave and enter the cell, while other molecules that are large such as protein molecules can not enter or leave the cell.