Answer: Attached below is the missing part of your question
answer 
Mutant A 
1) Requires tryptophan in the growth medium or from a donor mutant 
2) Must form nanotubes to obtain it's required amino acid in this scenario:
Mutant B 
1) Requires histidine in the growth medium or from a donor mutant 
2) Does not need to form nanotubes to obtain it's required amino acid in this scenario:
Step-by-step explanation:
Mutant A ( Over produces His and cannot produce Trp ) 
 1) Requires tryptophan in the growth medium or from a donor mutant ; This is because the Mutant is an auxotroph for tryptophan.
 2) Must form nanotubes to obtain it's required amino acid in this scenario:
This is because growth medium of the mutant is supplemented with histidine
Mutant B ( cannot produce His and overproduces Trp ) 
1) Requires histidine in the growth medium or from a donor mutant :
This is because Mutant B lacks the biosynthetic pathways necessary for histidine production
2) Does not need to form nanotubes to obtain it's required amino acid in this scenario: because the Mutant cell can easily take up the required amount of Histidine from its surroundings.