We hope that, by the end of this month, the cost of the maintenance of the tower __________.
would have been estimated
has been estimated
would estimate
will be estimated
Explanation: বাক্যে ভবিষ্যৎ সময় জ্ঞাপক শব্দ যেমন: By this time, By (time, month, year) By then, Next (time, month, year) ইত্যাদি থাকলে verb এর future perfect tense হয়। যেমন- By the time he arrives, we will have finished our home work. (রেফারেন্স: Master by Md. Jahangir Alam)।
