There are some principal factors underlying some very difficult problems to analytical chemists in environmental analytical: a. The range of analyte types is very wide. They vary from simple inorganic species at one end of the scale to complex bio-molecules at the other. b. Sample matrices are frequently complex and unknown. They may be solid, liquid or gaseous. c. Analytes may have to be measured at very low concentrations, e.g. a few ppb(μg. kg-1). d. Environmental programmes often generate very large number of samples and place a premium on automation. e. Some analyses can only be made at, or very close to, the sampling site.Readily portable and robust analytical equipment or remote sensing devices are thus required. Which of the above are correct?( )