They saved money diligently so that ____________.

• Tense এর নিয়মানুযায়ী, 
- So that, in order that, that যুক্ত বাক্যের ক্ষেত্রে, 
- Present + Future
- Past + Past Future  হয়। 

• So that, in order that, that affirmative হলে can/may এবং negative হলে will/ may not বসে।
• Affirmative এর ক্ষেত্রে,
- Structure 1:  Subject + V1+ So that/ in order that/ that + sub + can/may + verb এর base form.
- Structure 2:  Subject + V2+ So that/ in order that/ that + sub + could/might + verb এর base form.

• Negative এর ক্ষেত্রে,
- Structure 1:  Subject + V1+ So that/ in order that/ that + sub + will/may + not +verb এর base form.
- Structure 2:  Subject + V2+ So that/ in order that/ that + sub + would/might + not + verb এর base form.

• সুতরাং, সঠিক উত্তর হবে - they would not struggle financially.
- Complete sentence: They saved money diligently so that they would not struggle financially.