A quicker way to solve this is to spot the one statement that reads like an obvious contradiction. CAD programmes exist to fix the last mile problem of irrigation, water reaching the outlet is not the same as water reaching the root zone evenly. For that even spread to happen, the field surface has to be levelled and shaped properly, otherwise water pools in low spots and starves high spots. So any option claiming land shaping and levelling is not required goes directly against the purpose of CAD, which flags (C) as false immediately.
The remaining three, modernising irrigation and main drainage, building field channels to carry water to the field, and building field drains to remove excess water, are all textbook CAD components that work together to make on-farm water management effective.
Dropping the false statement (C) and keeping (A), (B) and (D) gives the matching option.
\[\boxed{\text{(A), (B) and (D) only}}\]