Protected base class members cannot be accessed by: a. friends of the base class.
b. friends of derived classes.
c. Functions that are not derived-class member functions.
d. Functions that are neither friends of the base class, derived-class member functions nor friends of a derived class.

The answer is "Option d".

Explanation:

This class members can be accessed by their member and the friend of there class, It is also known as the Members of the derived class from the basic class can be accessed by the protected and non-static member of the base class, and wrong choices can be described as follows:

Option a and Option b both are wrong because non-static member can't be accessed by there base or derived class. In option c, It is wrong because the function is a member function of the derived class.

answer: when the substance contain the two parts (polar and non-polar) like soap.

explanation:

soap is produced from the basic hydrolysis of ester "saponification", it is considered as a salt of hydrocarbons. the soap molecule contains the two parts: a polar group   (-coo-na+) and a non-polar group (r-hydrocarbon part). the polar group is called the head and the tail is the non-polar group. the polar group is hydrophilic in nature (water loving) and the non-polar group is hydrophobic in nature (water repelling).the polar/non-polar nature of a substance is useful that it can dissolve the non-polar substances by the polar part and also can dissolve the polar substances by the non-polar part. it commonly used in detergents and soaps.