When can contour lines touch each other

All of the following came out of china and were exchanged along the silk road, except a. papermaking b. block printing c. buddhism d. compasses select the best answer from the choices provided a b c d

The graph below plots the temperature and luminosity of stars on the main sequence.

Which statements describe sustainable development? multiple answer choice -fishing does not remove more fish from water systems than can be replaced by the number of fish that will be born to replace them. -sustainable development is development that is designed to improve the economic conditions in less-developed countries. -sustainable development is mainly a regional issue. -sustainable development means water is used at a rate that won't reduce the amount available for future use. - sustainable development policies only need to be concerned with environmental protection. - trees cannot be cut down faster than the number that will be replaced by new growth.