You are given a science question (easy-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each question.

All of the following are functions of a cell membrane except  
 (A) surrounding and protecting the contents of the cell. (B) releasing waste products from the cell. (C) producing energy for cell processes. (D) allowing gases to enter the cell.
C

Lichens are symbiotic organisms made of green algae and fungi. What do the green algae supply to the fungi in this symbiotic relationship?  
 (A) carbon dioxide (B) food (C) protection (D) water
B

On a field trip, a student holds a frog and reports that it has slippery skin. This is an example of  
 (A) a measurement (B) a prediction (C) an explanation (D) an observation

D