OG12-19,but+动名词

rainbowmanutd

The Iroquois were primarily planters, but supplementing their cultivation of maize, squash, and beans with fishing and hunting.
(A)    but supplementing (B)    and had supplemented (C)    and even though they supplemented (D)    although they supplemented (E)    but with supplementing
题目选D,没有什么疑问，但是对于A的but+doing,这种结构是正确的吗？A的解释里只是说不符合逻辑，可没说这种结构是不是正确的

spoiledchild

but是连词，逗号后面连词开头应该接句子。不知道我说的对否？