In a survey, as many as two-thirds of the respondents believe that the most important factor affecting the sense of safety at present is the level of income. Analyzing the sense of security of different income groups, it is found that those with a monthly income of 3,000 to 6,000 yuan are safe. It is significantly lower than those with a monthly income of 6000 ~ 8000 yuan. Therefore, the lower the income, the lower the sense of security,. Which of the following, if true, cannot weaken the above point? ['the cost of living is higher for people with an income of 3,000 to 6,000 yuan than other groups.', 'many people think that income is more stable than income.', 'people with an income of 1500 ~ 3000 yuan are more secure.', 'income is not the only factor affecting security, food, marriage, etc. all have an equally important role in security.']