the sp2 hybridized carbon of the acyl halide is less sterically hindered.
    
  the sp2 hybridized carbon of the acyl halide is more sterically hindered.
    
  the acyl halide has a lower energy transition state.
    
  the acyl halide has a higher energy transition state.
    
  A and C
    
  A and D
    
  B and C
    
  B and D