Carlos is trying to determine how music affects the growth of bean plants. He hypothesizes that classical music will cause a plant to grow at a higher rate than no music or rap music. He grows nine bean plants in similar lighting, temperature, and soil conditions. Three are exposed to classical music 24 hours a day, three are exposed to rap music 24 hours a day, and three are grown in complete silence. Carlos measures the growth of the plants every day and finds that the plants all seem to have the same rate of growth. What is missing from Carlos's scientific investigation? A: A specific hypothesis predicting a relationship between independent and dependent variables
B: Controlled variables to ensure only the independent variable is being changed
C: Experimental data collected regularly that can be recorded and analyzed
D: Research on what other scientists have observed and investigated on this topic

well what I think is that C is the correct answer

the answer is b & c i believe : )

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).