For Each Letter in the T-Accounts Below,calculate the Missing Amount

For each letter in the T-accounts below,calculate the missing amount and explain (in words)what each item represents.
$\begin{array}{cc}\text {Accounts Receivable }\\\hline\begin{array}{ll|l}\text { Jan. } 1&313\\&2,573&A\\\hline\text { Dee. } 31&295\\\hline\end{array}\end{array}\quad\quad$$\begin{array}{cc}\text { Prepaid Insurance }\\\hline\begin{array}{ll|l}\text { Jan } 1&25\\&B&42\\\hline\text { Dec. } 31&26\\\hline\end{array}\end{array}\quad\quad$$\begin{array}{cc}\text { Unearned Revenue }\\\hline\begin{array}{ll|l}&&240&\text { Jan }\\315&&C\\\hline&&253&\text { Dec. }\\\hline\end{array}\end{array}$