Sometimes when we do heavy exercise, anaerobic respiration takes place in our muscle cells. What is produced during this process?

Question

$\begin{array}{1 1} (a)\; \text{Alcohol and lactic acid} \\ (b)\; \text{Alcohol and $CO_2$} \\ (c)\; \text{Lactic acid and $CO_2$} \\ (d)\; \text{Lactic acid only} \end{array}$