Query related to notice u/s 139(9)

Hello,

One of my client sold his property during FY 2017-18. The possession of the property was transferred in FY 2017-18 whereas sale deed was executed in FY 2018-19 . Accordingly, as the possession was given to the buyer in FY 2017-18 capital gains on sale of property was offered in that year itself. However as the sale deed was executed in succeeding year i.e. FY 2018-19, the buyer deducted TDS on execution of sale deed, accordingly, TDS on sale of property was claimed in FY 2018-19.

Now, the assessee has received notice u/s 139(9) raising query gross income offered in return is lower than total income reflected in 26AS.

What remedy is available on this query?