Your CA has offered tax by using presumptive income section whereas he has selected some wrong business code and because of which you have received such notice so this defect needs to be rectified and return needs to be filed again.
It's not a major issue and since you are a technical professional you need to file return u/s 44Ada and show income @50% of total receipt.
So do you have foreign clients or are you a non resident?
You need to reply such notice within 30 days I guess otherwise they will reject your return and consider as if you have not filed return.
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