Which of the following is invalid deductively but might be part of a useful, philosophy homework help

Which of the following is invalid deductively but might be part of a useful inductive argument.

A.  If light is composed only of waves, then light cannot travel across empty space.  But light is composed only of waves, therefore light cannot travel across empty space.

B.  If light is composed only of particles, then light cannot exhibit diffraction patterns; and light can exhibit diffraction patterns, so light cannot be composed only of particles.

C.  If light is composed only of waves, then light cannot travel across empty space.  So suppose light cannot travel across empty space.  In that case light is composed only of waves.

D.  If light is composed only of particles, then light is composed only of waves.