Parallelism

As u have correctly pointed out this is a parallelism question here is the structure -

X, Y and Z

So , these X , Y and Z ( Listing something ) must be parallel.

Further the word improved must modify the word following it (since it acts like an adjective) .

Now lets check the options -

A. techniques, equipment, quality of seeds up to global standards, and have reduced wastage in cultivating

X = techniques
Y = equipment
z = have reduced wastage in cultivating

The highlighted part in red is not parallel to the other parallel elements of the sentence...

D. techniques, equipment, and quality of seeds up to global standards while reducing wastage in the cultivation of

Teh structure here is -

X = techniques
Y = equipment
z = quality of seeds

The elements are parallel.

Lets check further

D. techniques, equipment, and quality of seeds up to global standards while reducing wastage in the cultivation of

To the best of my knowledge " up to global standards " refers to all the three elements - techniques , equipment, and quality of seeds

And the red highlighted part means at the same time .

lets deconstruct the meaning of the sentence now -

Recent efforts of Panama's agricultural sector have improved techniques, equipment, and quality of seeds up to global standards while reducing wastage in the cultivation of its most promising crops such as bananas and coffee

Hope this helps !!