Which of the Following Properly Describes Constitutional Isomers

Which of the following properly describes constitutional isomers?

A) organic compounds with different molecular formulas
B) compounds with the same molecular formula,but a different order of attachment of atoms
C) compounds with the same molecular formula and order of attachment of atoms,but a different spatial arrangement of atoms
D) compounds with the same number of hydrogens,but a different number of carbons
E) compounds with the same number of carbons,but a different number of hydrogens