Least count, Precision, Accuracy

The smallest value that a scientific instrument can measure is called as 

True value of length of an iron rod is 1.23 m. A student measures it three times. The measurement he recorded is 1.21 m, 1.25 m and 1.24 m. The measurement is 

True weight of a glass sphere is 349 g. A student measures it three times. He records it as 341 g, 342 g and 342 g. The measurement is 

With the help of a stopwatch, a student measures the time taken for a fall of stone from a certain height. The actual time of fall is 3.7 second. His measurement is 3.7 second too. Which of the following is correct?

Error in a measurement can be due to following factors. Mark all that are correct.