Q.Many cells function properly and divide mitotically even though they do not have

Step 1. Eliminate the plasma membrane. Every single cell, without exception, is bounded by a plasma membrane - it is the structure that separates 'inside the cell' from 'outside the cell' in the first place. No cell, dividing or otherwise, can exist without one, so this cannot be the answer.

Step 2. Eliminate the cytoskeleton. The cytoskeletal network of microtubules and microfilaments is what physically builds the spindle apparatus that pulls chromosomes apart during mitosis. A cell attempting to divide mitotically without any cytoskeleton at all would have no mechanism to separate its chromosomes correctly, so this too is not a structure dividing cells manage without.

Step 3. Eliminate mitochondria. Mitochondria supply the ATP that powers the very large energy demand of active mitotic division (spindle assembly, chromosome movement, cytokinesis). While a few specialised or anaerobic cell types can survive with reduced mitochondrial activity, mitochondria are still present and needed in essentially every ordinary dividing eukaryotic cell, so this is a weaker candidate than the correct answer.

Step 4. Confirm plastids. Plastids - leucoplasts, chromoplasts and chloroplasts - are restricted entirely to plant and algal cells; they are completely absent from every animal cell and from the cells of fungi and most bacteria. Enormous numbers of cells across these kingdoms - the whole animal kingdom, for instance - divide mitotically and function perfectly well their entire lives without ever containing a single plastid. Even within plants themselves, many cell types (such as most root cells, away from the light) function and divide normally while never developing chloroplasts.

Check each option against which cell types actually possess it, and identify the one structure whose absence (in whole kingdoms of cells) still causes no problem with normal mitotic division.

• Assuming mitochondria are the 'odd one out' because a few unusual cell types (like mature mammalian RBCs) lack them - RBCs do not divide at all, so that example does not fit a question specifically about cells that DO divide mitotically.
• Forgetting that plastids are absent not just in animals but in the vast majority of a plant's own non-photosynthetic cells too.