In the sentence, certain words are in bold and numbered from A to E, which are the possible pairs to be interchanged. Choose the pair(s) of words which need to be interchanged to make the sentence grammatically correct and meaningful.

A (A) decrease of national weather services across Europe are (B) provided how to (C) compensate for the (D) coalition in the 700,000 climate observations normally (E) discussing per day by aircraft.