Tania has decided ___________ her computer.

To Selling

Sold

To sell

Sell

All of the above

Decide and sell are verbs here.

Usually to is used between two verbs.

Tania has decided to sell her computer means تانیا اپنا کمپیوٹر فروخت کرنے کا فیصلہ کرچکی ہے