Hi can anyone please help me figure this out. It’s a question from the JLPT prep book. The correct answer isn’t in the book only the blank it’s looking for. Blank 3
きのう かった おかしは (blank 1) (blank 2) (blank 3) (blank 4) でした
Answers:
1)いろ 2)きれい 3)が 4)まるくて
The book says the answer for blank 3 is ga but I can’t get my head around why
The answer I had which was incorrect was
きのう かった おかしは いる が まるくて きれい でした
Any help greatly appreciated
It’s いろ, not いる, so “color”. You wrote that the color is round. 
It should be きのう かった おかしは まるくて いろ が きれい でした
To expand upon why, you match the いろがきれい together to mean the colour is pretty, and then まるくて is in て form and doesn’t make sense to be at the end, so it must go first.
i always get that mixed up! thank-you for providing the correct answer 
Thanks so much for the clarification. I think I got confused with いろ being a noun or adj . が particles is a big weakness of mine