Secular trend is shown by -

Ans. is 'b' i.e., Coronary heart disease * The term secular trend implies changes in the occurrence of disease over a long period of time, generally several years or decades. There may be progressive increase or decrease in the occurrence of disease.* Examples -i) CHD, lung cancer, and DM have shown a consistent upward trend in developed countries.ii) TB, typhoid fever, diphtheria and polio have shown a declined trend in developed countries.