Q.60. The number of possible variations for unit cell having dimensions
a = 0.367 pm, b = 0.560 pm, c = 0.420 pm and α = β = γ = 90 ° will be
(1) 2
(2) 3
(3) 4
(4) 1

The sides are not equal. But the angles are equal and 90. This means it must be an Orthorhomic crystal lattice
Now Orthorhombic crystal lattice can have 4 variations of arrangement of atoms:
1) Simple cubic
2) End-centered
3) Body-cenetred
4) Face-centered 
Thus it has 4 possible variations

Thus the question wasn't how many types of crystal systems can have such dimensions, but how many variations are present in the system with these dimensions. 
Hope you understand
 

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