When examining cells in the lab you noticed a particular tissue sample is 45% of the cells in the mitotic phase how do you explain this observation

This observation shows that the tissue is growing or renewing itself.

Most tissues of the body grow by increasing their cell number which is achieved via mitosis (cell division). This kind of growth is highly regulated in order to maintain a balance between different tissues. On the other hand, cell division is involved in tissue renewal where many types of cells undergo continuous replacement. The example is skin. Skin cells are constantly being replaced by division of immature stem cells (the mature differentiated cells do not divide).  

"d.) carbon dioxide and hydrogen sulfide"