Who will you call upon?

A woman abandoned her husband & her four (4) year old son for her rich boyfriend & they both (woman & boy friend) eventually travelled to the U.S.A

Out of frustration & desperation the husband went & married another woman.

Unfortunately the 2nd woman couldn't bear a child for the husband.

 Despite her inability to bear a child, the 2nd woman took great care of the boy & treated him like her own son.

Few years later, the husband died in a car accident. 

The 2nd wife did everything in her power to educate the boy, she engaged in petty trade such as pepper, maggie, salt, palm oil, onion, tomatoes, etc, in the market square in order to sponsor the boy's schooling. 

The boy only knew his step mother as his real mother & there4, he called her Mama.

The real mother in the U.S.A did not for once find out about the wellbeing of her son thoughtless of sending a penny for the boy, even after she heard that her x-husband (son's father)  died in an accident.

Some years later, this boy grew up into a very intelligent young man waiting for his B.A Hons degree in Petroleum Engineering from the University.

The real mother who also could not bear another child in the U.S since she eloped with her boyfriend, realized that she had made a terrible mistake by abandoning her own son. 

She decided to return home to look for her son & present to him all her wealth acquired over the years in the States. 

She eventually found her son battling between life & death in the hospital for kidney failure. 

The Doctors demanded huge amount of money for the operation & the step mother couldn't afford it.

The real mother stepped in & paid all the hospital bills & donated one of her own kidneys & the son was saved.

Shortly after, the final results were out the son got a distinction & also got a five year (5) scholarship to pursue his Masters and PhD degrees in the U.K

At the presentation of the certificate, the Vice Chancellor gave the mic to the son to call his mother to come up stage & receive the certificate. 

The moment the Vice Chancellor made the statement, the real mother got up & arranged herself waiting to be called upon whilst the step mother sat down & looked at the boy with tears running her chick.

The answer is suspended..........

Assuming you are the son, who would you call on up stage? 

A) Real Mother

B) Step Mother

Remember only one person you should call. 
I need ur answers...