a-simplify block diagrams

b-modularize block diagrams

c-reduce the number of block diagram icons

d-all of the above

d)All of the above

Explanation: SubVI is considered as the stand VI which is the part of the LabVIEW programming.In the programming language , the small parts of the code are created that are named as subVI.

It is used for the block diagrams and front panels to make the program modular as they follow the feature of modularity. It can be called only from inside of VI. Thus, the modulation in the block diagram can be carried out through making it compact, reducing size, simplification clarity etc. So, all the given options are correct.