If a, b, c are positive real numbers, then for the system of equations
`x^(2)/a^(2)+y^(2)/b^(2)-z^(2)/c^(2)=1,x^(2)/a^(2)-y^(2)/b^(2)+z^(2)/(c^(2))=1,-x^(2)/a^(2)+y^(2)/b^(2)+z^(2)/c^(2)=1` there is :
A. no solution
B. exactly one solution
C. infinite folutions
D. None of these