Tobacco products have been identified has mutagens. however, some tobacco users develop cancer and some do not. the reason for this apparent inconsistency is

A mutation is single change or alternation or multiple changes in the genome of the living organism. A mutagen is an agent which causes mutation. Tobacco products have been identified has mutagens. Some tobacco users develop cancer and some do not this is because of many reasons like : high levels of nicotine and nitrogen is necessary for producing smoke concentration in products like beedi, cigarette which have collectively high mutagenic potential, the age of tobacco leaves used for making tobacco products (old age leaves induce mutagenic potency higher then young leaves), tobacco products with low sugar content will be less mutagenic then with higher sugar contents. Also, the frequency of use of tobacco products also affects the level of mutagenicity. Higher the frequency of use, higher will be chances of occurrence of mutation. Therefore, cause of cancer is chiefly dependent upon the composition of tobacco products and frequency of their use.  

starchy vegetables are high in carbohydrates.

starchy vegetables contain more carbohydrates than non-starchy vegetables.

explanation:

there are two primary categories of carbohydrates, essentially differentiated on the basis of their carbohydrate content (which is in the form of starch - a complex carbohydrate):

those vegetables which contain little amounts of starch are termed as non-starchy vegetables, and some examples include: artichokes, broccoli and bean sprouts.

vegetables high in their starch content are distinguished as starchy vegetables, and some examples include: potatoes, chickpeas and corn.

a. an idea which cannot be disproven!

explanation: